Methods of using electro-sensitive movable fluids

ABSTRACT

Provided is a method for creating fluid motion of an electro-sensitive movable fluid upon application of direct-current-voltage between two electrodes adjacent the fluid, the fluid having a conductivity σ, and a viscosity η located inside a triangle in a graph showing a relation between a conductivity σ plotted as abscissa, and a viscosity η, plotted as ordinate, of a fluid at the working temperature, said triangle having, as vertices, a point P indicated by the conductivity σ=4×10 −10  S/m and the viscosity η=1×10 0  Pa·s, a point Q indicated by the conductivity σ=4×10 −10  S/m and the viscosity η 1×10   −4  Pa·s, and a point R indicated by the conductivity σ=5×10 −6  S/m and the viscosity η 1×10   −4  Pa·s.

FIELD OF THE INVENTION

[0001] The present invention relates to electro-sensitive movable fluidswhich flow by application of a direct-current-voltage, methods of usingthe movable fluids and motors using the movable fluids.

BACKGROUND OF THE INVENTION

[0002] It is known that the characteristics of certain kinds ofdielectric fluids vary when the dielectric fluids are subjected toelectric fields. In case of liquid crystals, for example, when a voltageis applied to liquid crystal compounds in a liquid crystal phase (i.e.,intermediate phase between a solid phase and a liquid phase),orientation properties of the compounds are controlled to thereby adjustlight transmittance of the compounds, whereby visible images are formed.However, even if the liquid crystal compounds regulated by theorientation plates are placed in electric fields, they cannot flowfreely because they are not liberated from the regulation.

[0003] Also, some fluids are known to exert an effect of variation ofproperties such as viscosity (electrical rheology effect or WinslowEffect).

[0004] The fluids exerting electrical rheology effect or Wien effect aregenerally colloidal dispersions wherein solid components, such as silicagel, cellulose, casein and polystyrene ion exchange resins, are mixedwith insulating oils and dispersed in the oils, so that the storagestability of such fluids is low.

[0005] As lubricating oils for automobiles, those exhibiting electricalrheology effect have been proposed, but such lubricating oils are alsoheterogeneous and have a problem of low storage stability.

[0006] In Japanese Patent Laid-Open Publications No. 57274/1994 and No.73390/1994, inventions of electrosensitive compositions whereininsulating oils are blended with specific fluorine compounds aredisclosed.

[0007] The compositions disclosed in those publications are mixtures ofinsulating oils and fluorine compounds, and therefore they have aproblem in the storage stability. Additionally, there is a worldwidetendency to avoid the use of fluorine compounds in recent years.

OBJECT OF THE INVENTION

[0008] An object of the present invention is to provide anelectro-sensitive movable fluid which flows upon application of adirect-current-voltage, a method of using the movable fluid and a motorusing the movable fluid.

[0009] More particularly, the object of the invention is to provide anelectro-sensitive movable fluid, wherein jet flow is induced by theelectric energy of a direct-current-voltage applied to the movablefluid, said jet flow of the movable fluid being able to be taken out asmechanical energy such as rotational energy.

[0010] It is another object of the invention to provide an energyconversion method using the electro-sensitive movable fluid wherein theelectric energy of a direct-current-voltage applied to the movable fluidis converted to energy in the other form.

[0011] It is a further object of the invention to provide a novel motorusing the electro-sensitive movable fluid.

SUMMARY OF THE INVENTION

[0012] The electro-sensitive movable fluid of the invention comprises acompound having a conductivity σ and a viscosity η located inside arectangular triangle in a graph showing a relation between aconductivity σ, plotted as abscissa, and a viscosity η, plotted asordinate, of a fluid at the working temperature, said rectangulartriangle having, as vertexes, a point P indicated by the conductivityσ=4×10⁻¹⁰ S/m and the viscosity η=1×10⁰ Pa·s, a point Q indicated by theconductivity σ=4×10⁻¹⁰ S/m and the viscosity η=1×10⁻⁴ Pa·s, and a pointR indicated by the conductivity σ=5×10⁻⁶ S/m and the viscosity η=1×10⁻⁴Pa·s, or comprises a mixture of two or more kinds of compounds, saidmixture being adjusted to have a conductivity σ and a viscosity ηlocated inside said rectangular triangle.

[0013] The electro-sensitive movable fluid may be an inorganic compoundor an organic compound. When the electro-sensitive movable fluid is anorganic compound, this organic compound preferably is a chain orbranched, substantially dielectric fluid compound containing molecularend group composed of alkyl groups, outer ends of said groupsinactivated by hydrogen atoms bonding to the carbon atoms, saidmolecular end groups being united by bonding to each other at the innerends, in which the bonding hand of each carbon atom for constituting theend groups with the sealed ends is bonded to at least one hetero atomand further linked to a straight-chain divalent hydrocarbon group, whichmay have a hetero atom and may have a branch, through the hetero atom,or is bonded to a divalent hydrocarbon group which may have a heteroatom or may have a branch.

[0014] When a voltage is applied between at least two electrodesarranged in the electro-sensitive movable fluid of the invention, theelectro-sensitive movable fluid can be moved in the direction of oneelectrode to the other electrode.

[0015] Further, using the electro-sensitive movable fluid, the electricenergy can be converted to energy of other form by a method comprisingthe steps of arranging at least one pair of electrodes in theelectro-sensitive movable fluid, applying a voltage between theelectrodes to form jet flow of the electro-sensitive movable fluid at avelocity corresponding to the applied electric energy, and convertingfluid energy of the jet flow of the electro-sensitive movable fluid tomechanical energy capable of being taken out. In this case, the energyconversion using the electro-sensitive movable fluid can be controlledby a method comprising the steps of arranging at least one pair ofelectrodes in a container filled with the electro-sensitive movablefluid, applying a direct-current-voltage between the electrodes toconvert electric energy to fluid energy of the electro-sensitive movablefluid by changing the applied direct-current-voltage in a range of 0.1 Vto 10 kV to control the flow velocity and the flow direction of theelectro-sensitive movable fluid in proportion to the applieddirect-current-voltage, and converting the fluid energy of the movablefluid to mechanical energy capable of being taken out.

[0016] The first motor for electro-sensitive movable fluid (referred toas “RE type ECF motor” hereinafter, ECF: electro-conjugated fluid),which is preferably employed for the energy conversion, includes acontainer to be filled with an electro-sensitive movable fluid, a lid toclose the container by being engaged with the open top of the container,a cylindrical rotor rotatable inside the fluid container around arotating shaft borne by a shaft hole provided at the center of the lidand a bearing section provided at the center of the bottom of thecontainer, plural first electrodes which are electrically connected withexternal electrode terminals through the rotating shaft at the upperpart of the cylindrical rotor and arranged in the vertical direction onthe surface of the cylindrical rotor, and second electrodes which areelectrically connected with external electrode terminals through therotating shaft at the lower part of the cylindrical rotor and arrangedin non-contact with the first electrodes and in the vertical directionon the surface of the cylindrical rotor. The electro-sensitive movablefluid of the invention can drive the second motor for electro-sensitivemovable fluid (referred to as “SE type ECF motor” hereinafter) otherthan the RE type ECF motor. The SE type ECF motor includes a cylindricalcontainer to be filled with the electro-sensitive movable fluid, a lidof the container and a vane rotor, vanes of which detect motion of themovable fluid induced by application of a voltage to thereby rotate therotor. The cylindrical container is provided with slits where theelectrodes are arranged, and from the slits at least one pair ofelectrodes extend along the inner wall surface of the container.

[0017] As described above, the RE type ECF motor includes a container tobe filled with an electro-sensitive movable fluid, a lid to close thecontainer by being engaged with the open top of the container, acylindrical rotor rotatable inside the container around a rotating shaftborne by a shaft hole provided at the center of the lid and a bearingsection provided at the center of the bottom of the container, pluralfirst electrodes which are electrically connected with first externalelectrode terminals through the rotating shaft at the upper part of thecylindrical rotor and arranged in the vertical direction on the surfaceof the cylindrical rotor, and second electrodes which are electricallyconnected with second external electrode terminals through the rotatingshaft at the lower part of the cylindrical rotor and arranged innon-contact with the first electrodes and in the vertical direction onthe surface of the cylindrical rotor. In the case of this motor, when adirect-current-voltage is applied between the first and secondelectrodes, jet flow of the electro-sensitive movable fluid is producedin the fluid container, whereby the rotor can be rotated together withthe electrodes.

[0018] When a certain kind of a dielectric fluid (i.e.,“electro-sensitive movable fluid” of the. invention) is subjected to anelectric field, an electric force is generated in the fluid owing to thenonuniformity of electric conductivity and dielectric constant insidethe fluid. In the direct current field, the Coulomb force acting onspace charge dominates the dielectrophoretic force. This Coulomb forcecauses hydrodynamic instability, resulting in occurrence of convectionof the electro-sensitive movable fluid or a secondary motion of thefluid. These phenomena are called as “electrohydrodynamic (EHD)effects”.

[0019] The present inventors have found that the electric energy can bereadily converted to mechanical energy utilizing the EHD effects andsucceeded in specifying a dielectric fluid capable of exerting the EHDeffects. That is, the electro-sensitive movable fluid of the inventioninherently is a dielectric fluid, but when the movable fluid issubjected to an electric field, electric current is brought about,though it is very small. When a direct-current-voltage is applied to theelectro-sensitive movable fluid as described above, the movable fluid ismoved owing to the EHD effects, whereby jet flow of the movable fluid isgenerated. The intensity (or rate) of the jet flow varies with theapplied direct-current-voltage. Therefore, when the motion (jet flow) ofthe electro-sensitive movable fluid is captured and taken out, theelectric energy can be utilized as mechanical energy transformed fromthe electric energy.

[0020] The present inventors consider that the motion of theelectro-sensitive movable fluid in the invention is owing to the EHDeffects. This means that the present inventors consider that thephenomenon occurring in the invention can be related with the “EHDeffects”, but they do not conclude that the phenomenon occurring in theinvention is owing to the “EHD effects”.

BRIEF DESCRIPTION OF THE DRAWING

[0021]FIG. 1 graphically shows a relation between viscosity andconductivity of the dielectric fluid (electro-sensitive movable fluid).

[0022]FIG. 2 schematically shows an embodiment of the SE type ECF motorusing the electro-sensitive movable fluid and an embodiment ofarrangement of the electrodes.

[0023]FIG. 3 schematically shows an embodiment of the RE type ECF motorusing the electro-sensitive movable fluid and an embodiment ofarrangement of the electrodes.

[0024]1: SE type ECF motor

[0025]2: container (outer cylinder)

[0026]4: lid

[0027]3 a, 3 b, 3 c, 3 d, 3 e, 3 f, 3 g, 3 h: electrode

[0028]6: vane

[0029]18: vane rotor

[0030]22: electro-sensitive movable fluid

[0031]40: RE type ECF motor

[0032]41: container (outer cylinder)

[0033]42: second electrode

[0034]43: first electrode

[0035]44: lid

[0036]45: rotating shaft

[0037]46: cylindrical rotor

[0038]47: shaft hole

[0039]48: bearing section

[0040]49: bottom

[0041]50, 60: rotational contact point

[0042]52, 53: external terminal

[0043]FIG. 4 schematically shows a device to measure output torque ofthe SE type ECF motor and the RE type ECF motor in Example 5.

[0044]FIG. 5 shows an example of behaviors of the electro-sensitivemovable fluid when a direct-current-voltage is applied to the movablefluid contained in the container.

[0045]FIG. 6 schematically shows a fluidic components using theelectro-sensitive movable fluid.

[0046]FIG. 7 graphically shows a relation between rotational speed andapplied voltage and a relation between electric current and appliedvoltage in the SE type ECF motor.

[0047]FIG. 8 to FIG. 10 graphically show variability of rotationalspeed, output torque or motor output power density when dibutyldecanedioate is used as the electro-sensitive movable fluid and theapplied voltage, the number of vanes, the diameter of the rotor, thediameter of the fluid container or the number of electrodes is varied.

[0048]FIG. 11 schematically shows a device which is used in Example 7,etc. to measure output torque.

DETAILED DESCRIPTION OF THE INVENTION

[0049] The electro-sensitive movable fluid of the present invention, themethod of using the movable fluid, particularly the method of convertingelectric energy to mechanical energy using the movable fluid, and themotor capable of being driven by the use of the movable fluid aredescribed in detail hereinafter.

[0050] The electro-sensitive movable fluid of the invention can bespecified by the conductivity and the viscosity.

[0051] When the conductivity σ and the viscosity η of fluids (generallycalled “dielectric fluids”) are measured under the conditions of anelectric field intensity of 2 kVmm⁻¹ and a temperature of 25° C., thedielectric fluids are distributed as shown in FIG. 1.

[0052] Further, when the SE type ECF motor and the RE type ECF motor aredriven using the dielectric fluids, these fluids are classified into agroup capable of driving those motors and a group incapable of drivingthose motors. In FIG. 1, the fluids capable of driving the SE type ECFmotor and the RE type ECF motor are represented by the symbol ♦, andthose incapable of driving the motors are represented by the symbol ⋄.

[0053] The dielectric fluid serving as the electro-sensitive movablefluid of the invention comprises a compound having, at its workingtemperature, a conductivity σ and a viscosity η located inside arectangular triangle in a graph (FIG. 1) wherein the conductivity σ isplotted as abscissa and the viscosity η is plotted as ordinate, saidrectangular triangle having the following points P, Q and R as vertexes,or the fluid comprises a mixture of two or more kinds of compounds, saidmixture being adjusted to have a conductivity σ and a viscosity ηlocated inside the above rectangular triangle. TABLE 1 Conductivity (σ)Viscosity (η) Point P   4 × 10⁻¹⁰ S/m 1 × 10⁰ Pa · S (Point P⁰)preferably preferably   5 × 10⁻¹⁰ S/m 8 × 10⁻¹ Pa · S Point Q   4 ×10⁻¹⁰ S/m 1 × 10⁻⁴ Pa · S (Point Q⁰) preferably preferably   5 × 10⁻¹⁰S/m 2 × 10⁻⁴ Pa · S Point R   5 × 10⁻⁶ S/m 1 × 10⁻⁴ Pa · S (Point R⁰)preferably preferably 2.5 × 10⁻⁶ S/m 2 × 10⁻⁴ Pa · S

[0054] In Table 1, the points P⁰, Q⁰ and R⁰ are particularly preferablepoints as the vertexes of the triangle wherein the electro-sensitivemovable fluid of the invention is located.

[0055] The electro-sensitive movable fluid of the invention is asubstantially dielectric fluid. The conductivity σ of ordinarydielectric fluids, as measured at an electric field intensity of 2kVmm⁻¹ and a temperature of 25° C., is usually in the range of 1×10⁻¹S/M to 1×10⁻¹⁷ S/m. However, the electro-sensitive movable fluid of theinvention is a dielectric fluid having a conductivity σ of 4×10⁻¹⁰ to5×10⁻⁶ S/m, preferably 5×10⁻¹⁰ to 2.5×10⁻⁶ S/m. Further, the dielectricfluid employable as the electricity-sensitive working liquid of theinvention has a viscosity η of 1×10⁻⁴ Pa·s to 1×10⁰ Pa·s, preferably2×10⁻⁴ Pa·s to 8×10⁻¹ Pa·s.

[0056] The reason why the electro-sensitive movable fluid of theinvention has the above conductivity and viscosity is not clear, but itis assumably as follows.

[0057] In the below-described SE type ECF motor and RE type ECF motor,the important factor of controlling the rotary motion is a conductivityof the fluid. Occurrence of the EHD (electrohydrodynamic) motion of thefluid in a direct current field requires presence of free charge.Generation of the free charge results from dissociation of neutralmolecule and injection of charge from electrodes. It is thought thatfree charge is generated when the dielectric fluid having a conductivitywithin the above range is used as the electro-sensitive movable fluid ofthe invention and that upon application of a direct-current-voltage, jetflow of the electro-sensitive movable fluid is produced owing to thefree charge. It is also thought that the viscosity of theelectro-sensitive movable fluid has influence on the efficiency intransference of the kinetic energy of the fluid jet flow to the rotor.

[0058] The materials having such conductivity and viscosity includeorganic ones and inorganic ones. The electro-sensitive movable fluid ofthe invention may be either of organic and inorganic materials.

[0059] Some examples of the organic compounds which have the aboveproperties and are employable as the electro-sensitive movable fluid ofthe invention are given below.

[0060] (1) Dibutyl adipate (DBA)

(σ=3.01×10⁻⁹ S/m, η=3.5×10⁻³ Pa·s)

[0061] (6) Triacetin

(σ=3.64×10⁻⁹ S/m, η=1.4×10⁻² Pa·s)

[0062]

[0063] (11) Butyl cellosolve acetate

(σ=2.10×10⁻⁸ S/m, η=7.0×10⁻⁴ Pa·s)

[0064] (12) Butyl carbitol acetate

(σ=5.20×10⁻⁸ S/m, η=1.7×10⁻³ Pa·s)

[0065] (13) 3-Methoxy-3-methylbutyl acetate (Solfit AC)

(σ=8.30×10⁻⁸ S/m, η=6.0×10⁻⁴ Pa·s)

[0066] (14) Dibutyl fumarate (DBF)

(σ=2.65×10⁻⁹ S/m, η=3.5×10⁻³ Pa·s)

[0067] (17) Propylene glycol methyl ether acetate (PMA)

(σ=1.56×10⁻⁷ S/m, η=6.0×10⁻⁴ Pa·s)

[0068]

[0069] (18) Methyl acetyl ricinoleate (MAR-N)

(σ=1.30×10⁻⁸ S/m, η=1.3×10⁻² Pa·s)

[0070]

[0071] (20) Dibutyl itaconate (DBI)

(σ=1.46×10⁻⁸ S/m, η=3.5×10⁻³ Pa·s)

[0072]

[0073] (23) 2,2,4-Trimethyl-1,3-pentanediol diisobutyrate (trade name:Kyowanol D)

(σ=6.24×10⁻⁹ S/m, η=4.0×10⁻³ Pa·s)

[0074]

[0075] (26) Propylene glycol ethyl ether acetate (trade name:BP-Ethoxypropyl Acetate)

(σ=3.10×10⁻⁸ S/m, η=6.0×10⁻⁴ Pa·s)

[0076]

[0077] (27) 9,10-Epoxy butyl stearate (trade name: Sansocizer E-4030)

(σ=5.46×10⁻⁹ S/m, η=2.0×10⁻² Pa·s)

[0078]

[0079] (28) Tetrahydrophthalic acid dioctyl ether (trade name:Sansocizer DOTP)

(σ=6.20×10⁻¹⁰ S/m, η=4.0×10⁻² Pa·s)

[0080] (33) 1-Ethoxy-2-acetoxypropane

(σ=4.41×10⁻⁷ S/m, η=4.0×10⁻⁴ Pa·s)

[0081] (35) Linalyl acetate

(σ=1.82×10⁻⁹ S/m, η=1.3×10⁻³ Pa·s)

[0082]

[0083] (36) Dibutyl decanedioate

(σ=1.35×10⁻⁹ S/m, η=7.0×10⁻³ Pa·s)

[0084] When a combination of plural compounds is used as theelectro-sensitive movable fluid of the invention, the conductivity andthe viscosity of a mixture of the plural compounds can be made to belocated inside the triangle defined by the points P, Q and R shown inFIG. 1.

[0085] In other words, even if each of compounds has a conductivityand/or a viscosity out of the above range, a mixture of the compounds isemployable as the electro-sensitive movable fluid of the invention, asfar as the conductivity and the viscosity of the mixture are within theabove range, respectively.

[0086] For example, a mixture (37) (σ=2.60×10⁻⁹ S/m, η=9.8×10⁻³ Pa·s) of2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (trade name: Kyowanol M,σ=6.80×10⁻⁸ S/m, η=1.2×10⁻² Pa-s) and 2-ethylhexyl palmitate (tradename: Exepal EH-P, σ=2.60×10⁻¹⁰ S/m, η=9.5×10⁻³ Pa·s) in a mixing ratioof 1:4 by weight, each having a conductivity and a viscosity out of theabove range, is employable as the electro-sensitive movable fluid. Also,a mixture (38) (σ=4.17×10⁻⁹ S/m, η=5.0×10⁻³ Pa·s) of DAM (diallylmaleate, σ=7.8×10⁻⁷ S/M, η=2.5×10⁻³ Pa·s) and butyl stearate (tradename: Exepal BS, σ=3.1×10⁻¹⁰ S/m, η=8.5×10⁻³ Pa·s) in a mixing ratio of1:4 by weight, each having a conductivity and a viscosity out of theabove range, is employable as the electro-sensitive movable fluid.

[0087] The requisite of the electro-sensitive movable fluid of theinvention is that the movable fluid has the above-defined conductivityand viscosity. The conductivity and viscosity mentioned above aremeasured at room temperature, but these property values are known tovary depending on the measuring temperature. The conductivity and theviscosity defined in the invention are irrespective of the temperature.That is, even the compounds having a conductivity and a viscosity out ofthe above range at room temperature (25° C.) are employable as theelectro-sensitive movable fluids, as far as the conductivity and theviscosity of the compounds are within the above range at their workingtemperatures, e.g., high temperatures or low temperatures. For example,the compound (15), 2-ethylhexyl benzyl phthalate (trade name: PlacizerB-8), has a conductivity σ of 1.10×10⁻⁸ S/m and a viscosity η of7.8×10⁻² Pa·s at room temperature, and even if a direct-current-voltageof 6 kV is applied to the compound at 25° C., the SE type ECF motor orthe RE type ECF motor with the compound (25) cannot be driven. To thecontrary, a heated product (39) obtained by heating 2-ethylhexyl benzylphthalate at 100° C., has a conductivity σ of 9.90×10⁻⁹ S/m and aviscosity of 3.5×10⁻² Pa·s (at 100° C.), and therefore the SE type ECFmotor or the RE type ECF motor with the heated product (39) can bedriven by applying a direct-current-voltage of 6 kV to the product (39).

[0088] On the other hand, at room temperature (25° C), none of thebelow-described compounds have a conductivity σ and a viscosity ηlocated inside the triangle formed by the points P, Q and R in FIG. 1.Therefore, those compounds cannot drive the SE type ECF motor or the REtype ECF motor at 25° C. when they are used singly.

[0089] (2) Tributyl citrate (TBC)

(σ=5.71×10⁻⁷ S/m, η=2.0×10⁻² Pa·s)

[0090] (3) Monobutyl maleate (MBM)

(σ=2.60×10⁻⁵ S/m, η=2.0×10⁻² Pa·s)

[0091] (4) Diallyl maleate (DAM)

(σ=7.80×10⁻⁷ S/m, η=2.5×10⁻³ Pa·s)

[0092] (5) Dimethyl phthalate (DMP)

(σ=3.90×10⁻⁷ S/m, η=1.2×10⁻² Pa·s)

[0093] (7) Ethyl cellosolve acetate

(σ=7.30×10⁻⁵ S/m, η=9.0×10⁻⁴ Pa·s)

[0094] (8) 2-(2-Ethoxyethoxy)ethyl acetate

(σ=6.24×10⁻⁷ S/m, η=1.4×10⁻² Pa·s)

[0095] (9) 1,2-Diacetoxyethane

(σ=2.00×10⁻⁶ S/m, η=1.5×10⁻³ Pa·s)

[0096] (10) Triethylene glycol diacetate

(σ=5.20×10⁻⁷ S/m, η=8.1×10⁻³ Pa·s)

[0097] (15) 2-Ethylhexyl Benzyl phthalate (trade name: Placizer B-8)

(σ=1.10×10⁻⁸ S/m, η=7.8×10⁻² Pa·s)

[0098] (19) 2-Ethylhexyl palmitate (trade name: Exepal EH-P)

(σ=2.60×10⁻¹⁰ S/m, η=9.5×10⁻³ Pa·s)

[0099] (21) Polyethylene glycol monooleate (trade name: Emanone 4110)

(σ=3.75×10⁻⁷ S/m, η=8.0×10⁻² Pa·s)

[0100] (22) Butyl stearate (trade name: Exepal BS)

(σ=3.10×10⁻¹⁰ S/m, η=8.5×10⁻³ Pa·s)

[0101] (24) 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (trade name:Kyowanol M)

(σ=6.80×10⁻⁸ S/m, η=1.2×10⁻² Pa·s)

[0102] (25) Propylene glycol monoethyl ether

(σ=6.24×10⁻⁵ S/m, η=8.0×10⁻⁴ Pa·s)

[0103] (29) Tributyl phosphate (TBP)

(σ=2.20×10⁻⁶ S/m, η=2.2×10⁻³ Pa·s)

[0104] (30) Tributoxyethyl phosphate (TBXP)

(σ=1.10×10⁻⁵ S/m, η=9.0×10⁻³ Pa·s)

[0105] (31) Tris(chloroethyl) phosphate (CLP)

(σ=7.80×10⁻⁶ S/m, η=3.0×10⁻² Pa·s)

[0106] (32) Ethyl 2-methylacetoacetate

(σ=1.00×10⁻⁴ S/m, η=5.0×10⁻⁴ Pa·s)

[0107] (34) 2-(2,2-Dichlorovinyl)-3,3-dimethylcyclopropane carboxylicacid methyl ester (DCM-40)

(σ=2.60×10⁻⁵ S/m, η=5.5×10⁻³ Pa·s)

[0108]

[0109] The electro-sensitive movable fluid of the invention, which isidentified by the conductivity a and the viscosity η as described aboveand is an organic material, preferably has the following structure.

[0110] That is, the electro-sensitive movable fluid of the inventionpreferably comprises a chain or branched, substantially dielectric fluidcompound containing molecular end group composed of alkyl groups, outerends of said groups inactivated by hydrogen atoms bonding to the carbonatoms, said molecular end groups being united by bonding to each otherat the inner ends, in which the bonding hand of each carbon atom forconstituting the end groups with the sealed ends is bonded to at leastone hetero atom and further linked to a straight-chain divalenthydrocarbon group, which may have a hetero atom and may have a branch,through the hetero atom, or is bonded to a divalent hydrocarbon groupwhich may have a hetero atom or may have a branch.

[0111] The electro-sensitive movable fluid having the above structure ispreferably at least one compound selected from the compounds representedby the following formulas [I], [II], [III], [IV] and [V].

[0112] The compound represented by the following formula [I] isemployable as the electro-sensitive movable fluid of the invention.

[0113] In the formula [I], X¹ is a divalent group of 1 to 14 carbonatoms. This divalent group may be a straight-chain group or a branchedgroup. Further, X¹ may be a hydrocarbon group composed of a carbon atomand a hydrogen atom, and it may further have hetero atoms (atoms otherthan carbon atom and hydrogen atom), such as an oxygen atom, a nitrogenatom and a sulfur atom. Of such divalent groups, those having an oxygenatom are, for example, groups having an ether linkage or groups havingan ester linkage.

[0114] Examples of the straight-chain groups among the divalent groupsof 1 to 14 carbon atoms include —CH₂—, —CH₂CH₂—, —CH₂CH₂CH₂—,—CH₂CH₂CH₂CH₂—and —(CH₂)_(n)— (n is an integer of 5 to 14).

[0115] The branched hydrocarbon group is a divalent group having usually3 to 14 carbon atoms, preferably 4 to 14 carbon atoms, and some examplesthereof are given below.

[0116] In the formula [I], when X¹ is a divalent group having an oxygenatom, examples of the divalent groups having an ether linkage includethe following groups.

[0117] In the formula [I], when X¹ is a divalent group having an oxygenatom, examples of the divalent groups having an ester linkage includethe following groups.

[0118] In the formula [I], Y¹ and Z¹ are each independently an alkylgroup of 1 to 5 carbon atoms, and examples thereof include methyl,ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, tert-butyl, n-pentyland iso-pentyl. Each of Y¹ and Z¹ may be a straight-chain alkyl group ora branched alkyl group. Y¹ and Z¹ may be the same as or different fromeach other.

[0119] Listed below are some examples of the compounds represented bythe formula [I] wherein X¹, Y¹ and Z¹ are such groups as mentionedabove, which are suitably used as the electro-sensitive movable fluid.2,2,4-Trimethyl-1,3-pentanediol diisobutyrate

[0120] The compound represented by the following formula [II] isemployable as the electro-sensitive movable fluid of the invention.

[0121] In the formula [II], X² is a divalent hydrocarbon group of 2 to 9carbon atoms, preferably 2 to 5 carbon atoms, which may have a branch.Y² is a divalent alkyl group of 1 to 6 carbon atoms which may have abranch. Some examples of such alkyl groups are given below.

[0122] In the formula [II], Z² is an alkyl group of 1 to 6 carbon atomswhich may have a branch. Some examples of such alkyl groups are givenbelow.

[0123] In the formula [II], n is an integer of 1 to 4, preferably aninteger of 1 to 3, more preferably an integer of 1 or 2.

[0124] m is an integer of 1 or 2. When m is 1, A is a hydrogen atom.When m is 2, the compound of the formula [II] is a symmetric dimerhaving A as a bonding hand wherein groups which are each represented by(Z²—O—(X²—O)_(n)—CO—Y²)-are directly bonded to each other.

[0125] Listed below are examples of the compounds represented by theformula [II].

[0126] The compound represented by the following formula [III] isemployable as the electro-sensitive movable fluid of the invention.

[0127] In the formula [III], X³ is a monovalent group having carbonatoms (a), oxygen atoms (b) and hydrogen atoms (2a+1−2b) wherein a is aninteger of 1 to 25, b is 0, 1, 2 or 3, and a and b are numberssatisfying the condition of 2a+1>2b, preferably a monovalent group whichmay have one oxygen atom as an epoxy group or a carbonyl group and has 1to 17 carbon atoms. Y³ is a hydrocarbon group of 1 to 14 carbon atomswhich may have a branched chain and/or a carbon-to-carbon double bond,preferably a hydrocarbon group of 2 to 10 carbon atoms.

[0128] Listed below are examples of the compounds represented by theformula [III].

[0129] The compound represented by the following formula [IV] or [V] isemployable as the electro-sensitive movable fluid of the invention.

[0130] In the formulas [IV] and [V], R¹ and R² are each independently ahydrocarbon group of usually 1 to 15 carbon atoms, preferably 1 to 9carbon atoms, but they may be each independently a hydrocarbon grouphaving an atom other than carbon and hydrogen. R¹ and R² may be the sameas or different from each other.

[0131] In the formulas [IV] and [V], X is a divalent group representedby the following formula [VI] or [VII].

[0132] In the formula [VI], R³ and R⁴ are each basically a divalenthydrocarbon group of usually 1 to 5 carbon atoms, preferably 1 to 2carbon atoms. This hydrocarbon group may have a branch, and to thehydrocarbon group, an atom other than carbon and hydrogen may be bonded.R³ and R⁴ may be the same as or different from each other.

[0133] In the formula [VI], q and r are each independently 0 or aninteger of 1 or more, and when q or r is 0, R³ and R⁴ are eachindependently a single bond.

[0134] In the formula [VI], p is 0 or an integer of 1, 2 or 3. Thecyclic structure regulated by p may have a substituent, and the cyclicstructure may be partly or wholly hydrogenated.

—C_(n)H_((2n-2m))—  [VII]

[0135] In the formula [VII], n is an integer of 2 or more, and m is thenumber of double bonds contained in this group. That is, the grouprepresented by the formula [VII] has a double bond.

[0136] Listed below are examples of the compounds represented by theformula [IV] or [V].

[0137] Dialkyl itaconates

[0138] e.g., Dibutyl itaconate, e.g., Diethyl itaconate

[0139]

[0140] Alkyl acetyl ricinoleates

[0141] e.g., Methyl acetyl ricinoleate

[0142] Dialkyl fumarates

[0143] e.g., Dibutyl fumarate

[0144] e.g., Bis(2-ethylhexyl) fumarate

[0145] Dialkyl adipates

[0146] e.g., dibutyl adipate

[0147] e.g., Bis(2-ethylhexyl) adipate

[0148] Dialkyl azelates

[0149] e.g., Bis(2-ethylhexyl) azelate

[0150] e.g., Dibutyl azelate

[0151] Phthalic acid derivatives

[0152] e.g., Butyl benzyl phthalate

[0153] Dialkyl phthalates

[0154] e.g., Bis(n-octyl) phthalate

C₆H₄(COO-n-C₈H₁₇)₂

[0155] Dialkyl decanedioates

[0156] e.g., Dibutyl decanedioate

C₄H₉—O—OC—(CH₂)₈—CO—O—C₄H₉

[0157] e.g., Bis(2-ethylhexyl) decanedioate

[0158] Dialkyl naphthenates

[0159] e.g., Dibutyl naphthenate

[0160] Of the compounds represented by the formulas [I] to [V], thecompound employable as the electro-sensitive movable fluid of theinvention needs to have a conductivity σ and a viscosity η, at itsworking temperature, located inside the triangle formed by the points P,Q and R in the graph shown in FIG. 1. When the electro-sensitive movablefluid is an organic compound, the compound preferably has a structurerepresented by the formula [I], [II] or [III].

[0161] The compounds serving as the electro-sensitive movable fluids canbe synthesized by combining known synthesizing methods. Some compoundshaving the above structures are commercially available. As a matter ofcourse, not only the compounds prepared by the known synthesizingmethods but also the commercially available compounds can be used as theelectro-sensitive movable fluid of the invention. These compounds can beused after purified, if desired.

[0162] To the above-mentioned compounds, a small amount of hydrocarboncompounds having 5 to 10 carbon atoms can be added to give mixturesemployable as the electro-sensitive movable fluids of the invention.When the mixture containing a small amount of a hydrocarbon compound of5 to 10 carbon atoms is used as the electro-sensitive movable fluid, theelectric sensitivity of the movable fluid can be improved.

[0163] Examples of the hydrocarbon compounds of 5 to 10 carbon atomsinclude petroleum benzine, ligroin, hexane, pentane, cyclopentane,cyclohexane and benzene. It is particularly preferable to use petroleumbenzine and ligroin singly or in combination. The petroleum benzine isdefined by JIS K 8594 and is a hydrocarbon fraction of 5 to 8 carbonatoms having a distillation temperature of 50 to 80° C. The ligroin isdefined by JIS K 8937 and is a hydrocarbon fraction of 5 to 9 carbonatoms having a distillation temperature of 80 to 110° C.

[0164] The hydrocarbon compound of 5 to 10 carbon atoms is added to theelectro-sensitive movable fluid in an amount of usually 0.1 to 20% byweight, preferably 1 to 10% by weight. However, mixing of thosecompounds may cause decrease of the specific gravity of theelectro-sensitive movable fluid or increase of the current value, sothat the mixing ratio can be adjusted according to the use purpose. Thetotal amount of the hydrocarbon compound of 5 to 10 carbon atoms and thecompound exhibiting electric sensitivity is 100% by weight.

[0165] To the electro-sensitive movable fluid of the invention, variousadditives, such as metallic powders, substances to ascertain stabilityof the movable fluid, colorants for color development (e.g., dyes andpigments), viscosity modifiers to modify viscosity of the movable fluid,can be added. Further, biocides agents, mildewcides, solvents, etc. canbe also added.

[0166] When a direct-current-voltage is applied to the electro-sensitivemovable fluid of the invention, jet flow of the movable fluidcorresponding to the applied direct-current-voltage is formed.

[0167] For example, when the electro-sensitive movable fluid of theinvention having a conductivity and a viscosity located inside thetriangle formed by the points P, Q and R in FIG. 1, preferably having astructure represented by the above formula, is introduced in a containerprovided with electrodes shown in FIG. 5 and a direct-current-voltage isapplied, such jet flows of the electro-sensitive movable fluid as shownin FIG. 5 are produced. Therefore, if a vane rotor is equipped in thecontainer, convection of the electro-sensitive movable fluid collideswith vanes of the rotor to thereby rotate the rotor. That is, theelectric energy supplied to the electro-sensitive movable fluid of theinvention is converted to kinetic energy of fluid (i.e., jet flow of themovable fluid), and the kinetic energy is captured and taken out. Thus,the electric energy can be transformed to mechanical energy through theelectro-sensitive movable fluid.

[0168] The electro-sensitive movable fluid of the invention can be usedfor fluid control device (fluidics). The fluidics have a function toconvert an electric-signal to a fluid-signal, so that they can beapplied to, as it is called, fluid-computer. In the fluidics using theelectro-sensitive movable fluid of the invention, as shown in FIG. 6(A),electrodes 65, 66, 67 are arranged in a main tube 61 of a fluidtransport tube having plural branch tubes 62 a, 62 b, . . . Of theelectrodes, the electrode 65 is grounded to make it a negativeelectrode, while the electrode 66 is set to be a positive electrode.Then, a voltage is applied to the positive electrode. If a jet flow ofthe electro-sensitive movable fluid is given in the upward directioninside the main tube 61, a force to move the electro-sensitive movablefluid in the direction of the electrode 66 to the electrode 65 isgenerated. This force acts to push the upward jet flow in the transversedirection, whereby the jet flow is led to the branch tube 62 b. To thecontrary, when the electrode 67 is set to be a positive electrode and avoltage is applied thereto, the jet flow can be led to the branch tube62 a. Thus, the electric signals between the electrodes can be convertedto the kinetic signals of fluid.

[0169] As shown in FIG. 6(B), if the positions of the electrodes in thefluidics are varied so that the electrode 69 is set to be a positiveelectrode and that change-over of the negative electrode (ground point)between the electrode 68 a and the electrode 68 b is made possible, ajet flow of the electro-sensitive movable fluid is formed and thedirection of the jet flow can be controlled by performing change-over ofthe earth point (68 a, 68 b). Thus, the electric signals between theelectrodes can be converted to the kinetic signals of fluid.

[0170] In FIG. 2, an embodiment of an apparatus (SE type ECF motor) toconvert the electric energy to the mechanical energy using theelectro-sensitive movable fluid is shown, and an embodiment ofarrangement of the electrodes in the SE type ECF motor is also shown. InFIG. 3, an embodiment of a RE type ECF motor and an embodiment ofarrangement of the electrodes in the RE type ECF motor are shown.

[0171] Referring to FIG. 2, the SE type ECF motor 1 comprises acontainer 2 (bottomed cylindrical fluid container) to be filled with anelectro-sensitive movable fluid 22, a lid 4 of the fluid container 2,and a vane rotor 18 provided with vanes 6 which detect motion of themovable fluid 22 caused by application of a voltage to rotate the rotor.The upper rim of the bottomed cylindrical fluid container 2 is providedwith slits 13 for disposing electrodes 3 a . . . 3 h therein. In thefluid container 2, fixing parts 14, 15 are provided to fix theelectrodes 3 a . . . 3 h drawn inside through the slits onto the innerwall surface of the fluid container.

[0172] The center of the lid 4 is provided with a shaft hole 19 throughwhich a rotating shaft of the vane rotor 18 penetrates. The vane rotor18 comprises a bearing 23 provided at the center of the bottom of thefluid container and plural vanes 6 combined with the rotating shaftwhich is rotatably borne by the shaft hole.

[0173] The electrodes 3 a . . . 3 h are drawn inside the fluid container2 through the slits 13 and extend toward the bottom of the fluidcontainer 2 along the inner wall surface of the fluid container 2 sothat the rotation of the vane rotor 18 is not hindered. The electrodes 3a . . . 3 h are insulated from each other.

[0174] The electro-sensitive movable fluid 22 is filled in the fluidcontainer 2 in such an amount that the movable fluid does not overflowthe slits 13 and that the most parts of the vanes 6 are immersed in themovable fluid. Then, a direct-current-voltage is applied to theelectrodes 3 a . . . 3 h. The rotational direction of the vane rotor 18can be controlled by the arrangement of positive electrodes and negativeelectrodes.

[0175] For example, when the electrodes 3 a, 3 e are set to be positiveelectrodes, the electrodes 3 b, 3 f are set to be negative electrodes,and the electrodes 3 c, 3 d, 3 g and 3 h are set to be dummy electrodes,a jet flow in the direction of the electrode 3 a to the electrode 3 b ora jet flow in the direction of the electrode 3 e to the electrode 3 fdominates. Consequently, the rotational direction of the vane rotor 18can be made clockwise as shown by arrows in FIG. 2.

[0176] The voltage and the current applied to n of the electrodesrepresented by 3 a to 3 h . . . can be successively varied with time(variable application method). In the variable application method, theapplied voltage can be made low. Hence, this method is very useful inthe case where a high voltage is unable to be used or a large-sizedapparatus needs to be used.

[0177] The motor in which the electrodes 3 a . . . 3 h are fixed to theinner wall surface of the fluid container 2 is referred to herein as “SEtype ECF motor (stator-electrode type electro-conjugate fluid motor)”.

[0178] For example, a vane rotor 18 having eight vanes 6 is disposedinside the cylindrical fluid container 2, and the fluid container 2 isfilled with the electro-sensitive movable fluid to fabricate a SE typeECF motor shown in FIG. 2. When a direct-current-voltage is appliedbetween the electrodes 3 a . . . 3 h arranged shown in FIG. 2, the vanerotor 18 begins to rotate. As the number of the vanes 6 is increased,the rotational speed of the vane rotor 18 tends to be increased. As theinterval of the electrodes is narrowed, or as the number of pairs of theelectrodes is increased, the rotational speed tends to be increased. Therotational speed of the vane rotor 18 is increased or decreased inproportion to the applied voltage during the time from the initialrotation to the stable rotation.

[0179] The electro-sensitive movable fluid of the invention is able toconvert the electric energy to the mechanical energy using thebelow-described RE type ECF motor in place of the SE type ECF motor.

[0180]FIG. 3 is a perspective view schematically showing anotherembodiment (RE type ECF motor) of the motor using the electro-sensitivemovable fluid. In FIG. 3, an embodiment of arrangement of the electrodesin the RE type ECF motor is also shown.

[0181] Referring to FIG. 3, the motor (RE type ECF motor) 40 forelectro-sensitive movable fluid comprises a container 41 (bottomed fluidcontainer) to be filled with an electro-sensitive movable fluid 22 and alid 44 which is engaged with the open top to close the fluid container41. When the lid 44 is engaged with the upper open part of the fluidcontainer 41, the lid 44 and the fluid container 41 construct together aclosed housing.

[0182] The fluid container 41 for constituting the housing has a bottomand is generally made of a material which is corrosion resistant to theelectro-sensitive movable fluid filled therein. Examples of suchmaterials include synthetic resins, such as Teflon, polycarbonate andacrylic resins, ceramics, woods, metals and glasses. The fluid container41 can be formed from a conductive material such as metal (e.g.,stainless steel). The fluid container 41 formed from such a conductivematerial is preferably subjected to electrical insulation treatment orthe fluid container 41 is preferably formed from an insulating materialso as not to mar the insulated state between the electrodes.

[0183] The center of the bottom 49 of the fluid container 41 is providedwith a bearing section 48. Owing to the bearing section 48, the lowerend of a rotating shaft 45 is borne. The bearing section 48 forms arotational contact point 60 for electrically connecting the secondexternal terminals 52 and the second electrodes 42 with each other. Fromthe rotational contact point 60, conductors are led out along the innerwall surface of the fluid container 41. The conductors led out of thehousing form the second external terminals 52. At the bearing section 48which forms the rotational contact point 60 and bear the lower end of arotating shaft 45, a bearing mechanism can be provided to reducecoefficient of friction between the bearing section 48 and the rotatingshaft 45.

[0184] The top of the fluid container 41 is open to fill the containerwith the electro-sensitive movable fluid 22.

[0185] After the fluid container 41 is filled with the electricitymovable fluid 22, the lid 44 is engaged with the open top of the fluidcontainer 41 to form a closed housing. The lid 44 can be formed from thesame material as for the fluid container 41.

[0186] The lid 44 has a shaft hole 47 at the center thereof, throughwhich the rotating shaft 45 penetrates. The rotating shaft 47 isprovided with a rotational contact point 50 for supplying electricity tothe first electrodes 43 through the rotating shaft 45. At the rotationalcontact point 50, a bearing mechanism can be provided to reduce frictionbetween the rotating shaft 45 and the shaft hole 47. From the rotationalcontact point 50, conductors are led out to form the first externalterminals 53. As the conductors of the rotational points 50, 60, mercuryis employable.

[0187] In FIG. 3, the lid 44 is designed so as to be engaged with thefluid container 41, but the fluid container 41 and the lid 44 may bedesigned so that they are screwed up in order to improve the enclosedstate, or packing or the like can be interposed between the fluidcontainer 41 and the lid 44 to improve the enclosed state.

[0188] The rotational shaft 45 is divided into the upper part and thelower part by a cylindrical rotor 46 disposed in the fluid container 41,and the upper rotating shaft 45 a and the lower rotating shaft 45 b areelectrically insulated from each other. The upper rotating shaft 45 apenetrates through the shaft hole 47 provided at the center of the lid44 and is rotatably borne by the shaft hole, while the lower rotatingshaft 45 b is rotatably borne by the bearing section 48 provided at thecenter of the bottom 49 of the fluid container 41. Between the upperrotating shaft 45 a an the lower rotating shaft 45 b, the cylindricalrotor 46, which rotates together with the rotating shaft 45 in the fluidcontainer 41, is disposed. This cylindrical rotor 46 is in the form of acylinder having the rotating shaft 45 as a center axis of the rotationand is disposed in such a manner that space is formed between the rotor46 and the fluid container 41 so that the rotor 46 is not brought intocontact with the inner wall surface of the container 41. The ratio ofthe inner diameter of the fluid container 41 to the diameter of thecylindrical rotor 46 (inner diameter of fluid container 41/diameter ofrotor 46) is usually not less than 1.01, preferably 1.05 to 10.0. Whenthe motor is miniaturized by setting the inner diameter of the fluidcontainer 41 to not more than 30 mm and setting the ratio of the innerdiameter of the fluid container 41 to the diameter of the cylindricalrotor 46 within the range of 1.5 to 3.0, the rotational torque isincreased at the same rotational speed. In other words, this motor (REtype ECF motor) is characterized in that the performance can be improvedby being miniaturized.

[0189] The shape of the rotor 46 is not limited to a cylindrical one,and various shapes such as a rectangular parallelepiped shape, a shapehaving a number of protrusions on the surface and a shape havingstar-like section are employable according to the use purpose. Thecylindrical rotor 46 may be hollow. In this case, the hollow portion maybe made vacuum or may be filled with air, gas, liquid or solid so thatthe weight of the rotor is able to be optionally adjusted. By adjustingthe weight of the cylindrical rotor 46, the specific gravity of therotor 46 in the electro-sensitive movable fluid can be adjusted, wherebymotion or balance of the rotor 46 can be controlled.

[0190] On the surface of the cylindrical rotor 46, the first electrodes43 and the second electrodes 42 are arranged. The first electrodes 43are connected with the external terminals 53 through the upper rotatingshaft 45 a and the rotational contact point 50. The second electrodes 42are connected with the external terminals 52 through the lower rotatingshaft 45 b and the rotational contact point 60. The first electrodes 43are electrically insulated from the second electrodes 42.

[0191] The first electrodes 43 and the second electrodes 42 can beformed by extending conductors on the cylindrical surface of thecylindrical rotor 46.

[0192] The first electrodes 43 and the second electrodes 42 can bearranged at appropriate positions. FIG. 3 shows an embodiment ofarrangement of the electrodes when the cylindrical rotor 46 is seen fromabove. The first electrodes 43 and the second electrodes 42 are arrangedin such a manner that the interval angle θ between the first electrode43 and the second electrode 42 is usually 1.0° to 180°, preferably 3.0°to 90.0°. The interval angle θ varies depending on the number of theelectrodes arranged. Therefore, in order to set the interval angle θwithin the above range, the number of the first electrodes 43 and thenumber of the second electrodes 42 are each 1 to 60. In FIG. 3, thenumber 46 represents a cylindrical rotor, and the number 53 a representsa conductor led out from the first electrode 43, and this conductor maybe incorporated into the upper rotating shaft 45 a. Alternatively, theconductor and the upper rotating shaft 45 a may be united into one bodyby forming the upper rotating shaft 45 a itself from a conductivematerial.

[0193] Likewise, a conductor 52 a is lead out from the second electrode42, and this conductor may be incorporated into the lower rotating shaft45 b. Alternatively, the conductor and the lower rotating shaft 45 b maybe united into one body by forming the lower rotating shaft 45 b itselffrom a conductive material.

[0194] The fluid container 41 having the above-described structure isfilled with the electro-sensitive movable fluid 22.

[0195] The motor in which the electrodes are arranged on the surface ofthe cylindrical rotor 46 is referred to herein as “RE type ECF motor(rotor-electrode type electro-conjugate fluid motor)”.

[0196] In FIG. 3, an embodiment of the RE type ECF motor wherein thecylindrical rotor 46 formed from a column-like material is disposed inthe fluid container 41 is shown. On the top of the cylindrical rotor 46,the rotating shaft 45 a made of, for example, a metallic round bar isprovided.

[0197] A plus terminal and a minus terminal of a direct current powersource are connected with the external terminal 52 and the externalterminal 53, respectively, so that the direct-current-voltage can beapplied between the first electrode 43 and the second electrode 42 ofthe RE type ECF motor. One of the first electrode 43 and the secondelectrode 42 is set to be a positive electrode and the other is set tobe a negative electrode, and in this case, any one of them may be set tobe a positive electrode. When the direct-current-voltage is applied, theelectro-sensitive movable fluid 22 begins to flow. With the flow (jetflow) of the electro-sensitive movable fluid 22, the cylindrical rotor46 begins to rotate. The current generated when thedirect-current-voltage is applied is very small, usually not more than0.5 mA, in many cases not more than 20 μA because the electro-sensitivemovable fluid used in the invention is substantially nonconductive.

[0198] By applying a direct-current-voltage to the electro-sensitivemovable fluid of the invention filled in the SE type ECF motor or the REtype ECF motor having the above structure, the SE type ECF motor or theRE type ECF motor can be driven.

[0199] Next, a method of driving, for example, the SE type ECF motor bythe use of the electro-sensitive movable fluid of the invention isexplained. This motor is so fabricated that the motor comprises aplastic vane rotor having eight vanes and a plastic fluid container of10 mm in outer diameter, 8 mm in inner diameter and 20 mm in height, andthat four pairs of electrodes made of copper wire of 0.3 μm in diameterare arranged on the inner surface of the fluid container. This SE typeECF motor is filled with the electro-sensitive movable fluid and thendriven. The rotational speed of the SE type ECF motor, the appliedvoltage and the current can be measured in the following manner. As forthe rotational speed, a plastic disc is fitted to the rotating shaft ofthe SE type ECF motor as shown in FIG. 4(a). The rotation of the plasticdisc is detected by a photo interrupter to measure the rotational speedof the SE type ECF motor. As for the current, series resistance of 1 MΩis inserted between the SE type ECF motor and the ground as shown inFIG. 4(b). From the potential difference caused by the resistance, thecurrent can be measured. As for the voltage, Zener diode is connected inparallel with the resistance, and the voltage can be measured through avoltage follower using an OP amplifier having sufficiently high inputimpedance.

[0200] For example, a direct-current-voltage of usually 0.1 V to 10 kV,preferably 10 V to 7.0 kV, is applied to the electro-sensitive movablefluid of the invention filled in the above-mentioned apparatus. In thiscase, the current is usually 0.001 to 100 μA, preferably 0.05 to 10.0μA, and therefore the power supplied to the SE type ECF motor or the REtype ECF motor (i.e., between the electrodes) is 1×10⁻¹⁰ to 1.0 W,preferably 5×10⁻⁷ to 7×10⁻² W.

[0201] The applied voltage can be appropriately varied depending onscale of the apparatus, kind of the electro-sensitive movable fluid ofthe invention, construction of the apparatus, etc., but with the provisothat the same apparatus and the same fluid are used under the sameconditions, the rotational speed varies in proportion to the appliedvoltage.

[0202] In FIG. 7, an example of a relation between the applied voltageand the rotational speed and an example of a relation between theapplied voltage and the current are shown. That is, FIG. 7 shows arelation between the applied voltage and the rotational speed and arelation between the current and the rotational speed given when avoltage up to 6 kV is applied to the SE type ECF motor. As shown in FIG.7, there are constant proportional relations between the applied voltageand the rotational speed and between the applied voltage and thecurrent.

[0203] The control of the rotational speed owing to the control of thevoltage can be performed also in the RE type ECF motor using theelectro-sensitive movable fluid as well as in the SE type ECF motor.

[0204] The mechanism of driving the SE type ECF motor or the RE type ECFmotor by the use of the electro-sensitive movable fluid of the inventionhas not been clarified yet. However, such jet flows as shown in FIG. 5are confirmed to be produced when a voltage is applied to theelectro-sensitive movable fluid, and it is considered that the jet flowsbecome a rotational propulsion force of the motor.

[0205] Periodically, the motors driven in high electric fields by theuse of dielectric fluids have attracted the attention of scientists, andsome reports have been made. For example, more than 40 years ago, therewas a report that a glass bar having a diameter of a few mm placedbetween parallel plate electrodes, which were immersed in a dielectricfluid, began to rotate at a few thousands rpm upon application of about10 kV. The explanation for occurrence of this phenomenon is as follows.The charge generated on the glass bar surface is attracted by theelectrode of the opposite polarity to slightly rotate the glass bar, atthis instant the polarization disappears, and the repetition ofattraction of the charge and disappearance of the polarization resultsin occurrence of constant rotation. In this explanation, there is nodirect relation between the conductivity of the fluid and the rotarymotion of the glass bar. The motor utilizing the above phenomenon is ofabout a few mm, and it is not reported that a large motor such as the SEtype ECF motor or the RE type ECF motor is able to be rotated.

[0206] The above theory cannot explain the mechanism of convertingelectric energy to mechanical energy through the SE type ECF motor orthe RE type ECF motor using the electro-sensitive movable fluid of theinvention, because the conductivity and the viscosity of theelectro-sensitive movable fluid are very important factors of the driveof the motor in the invention.

[0207] The mechanism of converting the electric energy to the mechanicalenergy through the SE type ECF motor or the RE type ECF motor of theinvention is investigated below based on the matters having been alreadyconfirmed.

[0208] The ionic mobility has been reported to be of the order of 10⁻⁸m²V⁻¹S⁻¹ in a fluid having a viscosity of a few mPa·s. Assuming that thehydrodynamic radius of ions is within the range of 0.5 to 1.2 nm, theionic mobility can be estimated, through the Stokes-Einstein equation,as 5×10⁻³ m/s in an electric field of 0.5 kVmm⁻¹ (5 kV applied betweenelectrodes at an interval of 10 mm). Also, assuming that the ionicmotion directly brings about drag flow of the fluid to thereby rotatethe motor, the rotational speed may be much slower. Because the SE typeECF motor and the RE type ECF motor rotate at a higher speed by twofigures as much as the above-assumed rotational speed, it is difficultto infer that the ionic motion directly brings about a rotary motion ofthe rotor. When a high voltage is applied to a dielectric fluid asdescribed above, a secondary motion of fluid such as convection or chaosis sometimes brought about. According to the computing simulation on theelectrohydrodynamic (EHD) convection under such conditions that thegravitational effect is negligibly small (microgravity conditions), thevelocity of the secondary flow is assumed to be about 0.02 m/s at anelectric Rayleigh number of 6,000 where the Coulomb force is much largerthan the viscous force. However, this value is a little smaller than theflow velocity observed when the electro-sensitive movable fluid of theinvention is used, so that the mechanism of the high speed rotation ofthe rotor cannot be completely explained by only the EHD convection. TheEHD convection referred to herein is a non-linear phenomenon controlledby continuous equation, kinetic equation, Maxwell equation and chargetransfer equation.

[0209] Yabe and Maki have found that when a high voltage of 10 kV isapplied to a ring electrode and a plate electrode arrangedaxisymmetrically, a jet flow of fluid is created in the vicinity of thecenter of the ring in the direction away from the plate electrode, andthey made a report on the findings (see: Int. J. Heat Mass Transfer 31,407 (1988)). It has been reported that the above phenomenon is such aphenomenon that the fluid attracted from the circumference of the ringis jetted after the fluid passed through gap between the ring and theplate electrode, and the flow velocity sometimes exceeds 1 m/s. Themechanism of occurrence of the jet flow is not clear, but the velocityof the jet flow is comparable to the circumferential velocity of therotor in the invention. Since the velocity of the jet flow seems to besimilar to that of the electro-sensitive movable fluid when adirect-current-voltage is applied to the movable fluid, those mechanismmay have some relevancy each other. However, the above fluid composition(flon R113 +ethanol) shows quite different from the movable fluid of theinvention, and the above apparatus is also different from that of theinvention. For reasons, the relevancy is still unknown.

[0210] The description on the mechanism of the present invention is justan inference which is made by the present inventors based on theconfirmed facts and which is intended to assist understanding of thepresent invention. Therefore, it should be construed that the inventionis not limited to the inference.

[0211] The electro-sensitive movable fluid of the invention flows uponapplication of a direct-current-voltage. The jet flow of the movablefluid can be converted to mechanical energy such as rotational energyand can be taken out as the mechanical energy. Further, when the voltageapplied to the electro-sensitive movable fluid of the invention ischanged to vary the supplied electric energy, the electric energy can beconverted to energy of other form in proportion to the amount of theelectric energy supplied by the applied voltage, with steplesscontrolling the voltage. Accordingly, the electro-sensitive movablefluid of the invention can be used in various fields, for example, afield utilizing the motion of the electro-sensitive movable fluidbetween the electrodes applied with a direct-current-voltage and a fieldutilizing the rotational energy which is converted from the jet flowmotion of the electro-sensitive movable fluid produced by application ofa direct-current-voltage and then taken out of the apparatus. The SEtype ECF motor and the RE type ECF motor are typical embodiments. The SEtype ECF motor and the RE type ECF motor utilizing the energy conversioncontrol method of the invention is improved in the performance when theyare miniaturized. Besides, these motors have simple structures, so thatthey are very effective as inexpensive, trouble-free micromotors.

[0212] As described above, the electro-sensitive movable fluid can beutilized for the rotary mechanism in which the rotor equipped withelectrodes is rotated. Further, if a small fragment equipped withelectrodes is placed in the electro-sensitive movable fluid and adirect-current-voltage is applied to the electrodes from the outside,the small fragment is able to freely swim like fish in the movable fluidowing to a propulsion force supplied by the fluid jet flow producedbetween the electrodes.

[0213] Furthermore, if a small fragment equipped with electrodes on itsbottom surface is floated on the electro-sensitive movable fluid of theinvention and a direct-current-voltage is applied to the electrodes, thesmall fragment is able to freely sail like a boat on the movable fluidsurface owing to a propulsion force of the fluid jet flow.

[0214] Instead of application of the direct-current-voltage from theexternal electric source, the direct-current-voltage can be directlyapplied by means of solar panel, light piezoelectric element or PLZTelement capable of generating high voltage by irradiation with light. Inthis case, the solar panel or the PLZT element is fitted to the drivingsection together with the electrodes and irradiated with light insteadof applying a voltage from the external electric source, whereby no wirefrom the external electric source is necessary. As a result, the abovefragment (fragment moving like fish or boat) has a high degree offreedom in its motion, and even in a transparent closed container, themotion of the fragment can be controlled without restraint. In otherwords, for an innter work where human beings cannot get into, e.g.,atomic power station, the system using the electro-sensitive movablefluid of the invention can be used as an inner work apparatus capable ofbeing driven and controlled by irradiation with light through protectiveglass; therefore, it is very useful.

[0215] In the field of computer technology, a great number ofsemiconductors are used for computers. When the computers are driven,the semiconductors generate heat. Therefore, most of the computers needsto be equipped with built-in fans to cool the computers. The coolingfans generally use electromagnetic motors, and such cooling fansgenerate heat during working. Consequently, the cooling fans must coolnot only the semiconductor chips which generate heat during working butalso the electromagnetic motors which drive the fans, resulting in largepower consumption. Moreover, the size of the electromagnetic motors islarge for the size of the semiconductor chips, and this is an obstacleto miniaturization of computer or conservation of energy. On the otherhand, the ECF cooling fans using the electro-sensitive movable fluid,which comprise motors fabricated based on the technique of the inventionand cooling vanes, hardly generate heat. Besides, they can be driven bya low power and can be miniaturized. Therefore, the ECF cooling fans aremost suitable for small computers. In addition, miniaturization of themotors makes it possible to equip the cooling fan for everysemiconductor which generates heat. That is, on-chip type cooling fansare employable.

[0216] In another use, a linear motor capable of being driven by alinear jet flow of the electro-sensitive movable fluid is available byusing a rectangular parallelepiped fluid container in place of thecylindrical fluid container and arranging electrodes on the innersurface of the container. As another mechanism, a linear motor using theabove-mentioned fish-like fragment provided with electrodes can beconstructed.

[0217] The electro-sensitive movable fluid of the invention is specifiedby the conductivity and the viscosity at a temperature at which themovable fluid is used, and therefore the fluid may be either of anorganic compound and an inorganic compound. Accordingly, theelectro-sensitive movable fluid of the invention also includeshigh-temperature inorganic fluids having the prescribed conductivity andviscosity, such as lava extruded from volcanoes (lava flow). If thehigh-temperature inorganic fluids such as lava flow have the viscosityand conductivity defined by the present invention, those fluids exhibitbehaviors equivalent to those of the electro-sensitive movable fluid ofthe invention. Hence, if the lave flow satisfying the requisite of theelectro-sensitive movable fluid of the invention were provided with hugeelectrodes and a direct-current-voltage were applied to the electrodes,it might be feasible to control a path of the lava flow (direction ofthe lave flow) by the applied direct-current-voltage.

[0218] Since the electro-sensitive movable fluid of the invention can bespecified by the viscosity and the conductivity at the workingtemperature as described above, driving of motors is feasible byapplication of a direct-current-voltage even in the extremelyhigh-temperature environment where the conventional motors are difficultto use, provided that the viscosity and the conductivity of the fluidsused for the motors are within the above-defined range.

EFFECT OF THE INVENTION

[0219] The properties required for the electro-sensitive movable fluidof the invention and the ranges of the properties are specified by thepresent inventors. That is, the properties required for theelectro-sensitive movable fluid of the invention are viscosity andconductivity at a temperature at which the movable fluid is used, and nophenomenon suggesting participation of other properties has not beenfound. The temperature is a mere condition to specify the conductivityand the viscosity in the use of the electro-sensitive movable fluid.

[0220] Accordingly, the requisite of the electro-sensitive movable fluidof the invention is only that the fluid satisfies the above-definedconductivity and viscosity, irrespective of an organic or inorganiccompound. That is, the present invention gets out of the preconceivedideas that electro-sensitive movable fluids are organic compounds andthereby extends a possibility of using the inorganic compounds as theelectro-sensitive movable fluids.

[0221] When a direct-current-voltage is applied to the electro-sensitivemovable fluid of the invention provided with positive and negativeelectrodes, the movable fluid moves between the electrodes. In otherwords, the electro-sensitive movable fluid of the invention movesbetween the electrodes by mere application of a direct-current-voltagewithout using any physical actuation means such as pump. Therefore, theelectric energy can be directly converted to kinetic energy by the useof the electro-sensitive movable fluid of the invention.

[0222] Owing to the movement of the electro-sensitive movable fluid, acontinuous, constant and systematic motion of the movable fluid, such asconvection of the fluid, can be formed in the container.

[0223] By taking the continuous, constant and systematic motion of themovable fluid out of the container in the form of, for example,rotational energy, the electric energy can be transformed to clean andquiet kinetic energy.

[0224] Further, the conversion of the electric energy to the kineticenergy is performed by mere applying a direct-current-voltage to aspecific single material, so that it is unnecessary to mix pluralcompounds to prepare a fluid. Furthermore, the electric sensitivity isdetermined by the properties inherent in the single compound,variability in the electric sensitivity, which may be caused by themixing ratio in the case of using mixtures, is small.

[0225] Since the electro-sensitive movable fluid of the invention is astable ester compound, it is quite safe to the human body. Moreover,since the movable fluid substantially contains no halogen atoms,environmental pollution of the earth-caused by the halogen atoms doesnot brought about.

[0226] By the use of the electro-sensitive movable fluid of theinvention, an extremely small sized actuator can be manufactured, andbecause of its simple internal structure, the actuator is almost freefrom troubles.

[0227] The electro-sensitive movable fluid of the invention works uponapplication of a direct-current-voltage as described above, and thecurrent is very low under those conditions. Hence, the SE type ECF motoror the RE type ECF motor using the electro-sensitive movable fluid ofthe invention can be driven for a long period of time by means ofsmall-sized batteries. In addition, these motors have simple structures,they are almost free from troubles, and they are able to convert theelectric energy to the kinetic energy at low costs.

[0228] Production of a jet flow of the electro-sensitive movable fluidof the invention upon application of a voltage means that the appliedelectric energy is directly converted to the kinetic energy. Therefore,if a fluid begins to flow upon application of a voltage, this fluid isan electro-sensitive movable fluid. A fluid, which shows a high flowvelocity when the applied voltage is made constant, is anelectro-sensitive movable fluid capable of preferably converting theelectric energy to the kinetic energy.

[0229] Furthermore, since the jet flow of the electro-sensitive movablefluid of the invention can be produced when an electric field is formed,the movable fluid can be applied to the above-mentioned various uses.

EXAMPLE

[0230] The present invention will be further described with reference tothe following examples, but it should be construed that the invention isin no way limited to those examples.

Example 1

[0231] The compounds (1) to (36) listed below were measured on theviscosity and the electric resistance (conductivity) at 25° C.Measurement of the viscosity and the electric resistance was performedby the use of a rheometer (Rheo-Stress RS100 of HAAKE Co.). In detail,the compound was sandwiched between two discs each having a diameter of3.5 cm, and thereto was applied a direct-current-voltage of 2 kV tomeasure the conductivity (S/m upon application of 2 kV/mm). In the samestate, the viscosity of the compound was measured with rotating one ofthe discs. The values of the conductivity and the viscosity referred toin herein are those determined by the above methods.

[0232] The compound was filled in such a SE type ECF motor as shown inFIG. 2. Then, a direct-current-voltage of 6 kV was applied to thecompound at 25° C. to examine whether the vane rotor rotated or not andto measure the rotational speed when the rotor rotated.

[0233] In the SE type ECF motor used herein, the inner diameter of thebottomed cylindrical container was 20 mm, the number of vanes was 8, andeach vane had a height of 35 mm and a width of 17 mm. When 12 ml of themovable fluid was introduced into the container, the vanes werecompletely immersed in the fluid.

[0234] The SE type ECF motor was provided with 4 electrodes. The firstand the third electrodes were set to be negative electrodes, and thesecond and the fourth electrodes were set to be positive electrodes.These four electrodes were arranged in such a manner that the intervalangle between the first and the third electrodes and the interval anglebetween the second and the fourth electrodes were each 180° and theinterval angle between the first and the second electrodes and theinterval angle between the third and the fourth electrodes were each45°.

[0235] Into the SE type ECF motor having the above structure, 12 ml ofthe fluid was introduced, and a direct-current-voltage of 6 kV wasapplied between the electrodes to examine whether the SE type ECF motorwas driven or not and to measure the rotational speed when the motor wasdriven. The conductivity, the viscosity and the electric sensitivity ofthe dielectric fluids used are set forth in Table 3. TABLE 3 CompoundConduc- Viscosity Electric Sensitivity (™:trademark) tivity (S/m) (Pa ·s) (6 kV) (I) (1) DBA 3.01 × 10⁻⁹ 3.5 × 10⁻³ ♦driven at 147 rpm (2) TBC5.71 × 10⁻⁷ 2.0 × 10⁻² ⋄not driven (3) MBM 2.60 × 10⁻⁵ 2.0 × 10⁻² ⋄notdriven (4) DAM 7.80 × 10⁻⁷ 2.5 × 10⁻³ ⋄not driven (5) DMP 3.90 × 10⁻⁷1.2 × 10⁻² ⋄not driven (6) Triacetin ™ 3.64 × 10⁻⁹ 1.4 × 10⁻² ♦driven at77 rpm (7) Ethyl cellosolve acetate 7.30 × 10⁻⁵ 9.0 × 10⁻⁴ ⋄not driven(8) 2-(2-Ethoxyethoxy) ethyl 6.24 × 10⁻⁷ 1.4 × 10⁻² ⋄not driven acetate(9) 1,2-Diacetoxyethane 2.00 × 10⁻⁶ 1.5 × 10⁻³ ⋄not driven (10)Triethylene glycol acetate 5.20 × 10⁻⁷ 8.1 × 10⁻³ ⋄not driven (11) Butylcellosolve acetate 2.10 × 10⁻⁸ 7.0 × 10⁻⁴ ♦driven at 129 rpm (12) Butylcarbitol acetate 5.20 × 10⁻⁸ 1.7 × 10⁻³ ♦driven at 155 rpm (13) SolfitAC ™ 8.30 × 10⁻⁸ 6.0 × 10⁻⁴ ♦driven at 158 rpm (14) DBF 2.65 × 10⁻⁹ 3.5× 10⁻³ ♦driven at 178 rpm (15) Placizer B-8 ™ 1.10 × 10⁻⁸ 7.8 × 10⁻²⋄not driven (17) PMA 1.56 × 10⁻⁷ 6.0 × 10⁻⁴ ♦driven at 162 rpm (18)MAR-N ™ 1.30 × 10⁻⁸ 1.3 × 10⁻² ♦driven at 53 rpm (19) Exepal EH-P ™ 2.60× 10⁻¹⁰ 9.5 × 10⁻³ ⋄not driven (20) DBI 1.46 × 10⁻⁸ 3.5 × 10⁻³ ♦drivenat 167 rpm (21) Emanone 4110 ™ 3.75 × 10⁻⁷ 8.0 × 10⁻² ⋄not driven (22)Exepal BS ™ 3.10 × 10⁻¹⁰ 8.5 × 10⁻³ ⋄not driven (23) Kyowanol D ™ 6.24 ×10⁻⁹ 4.0 × 10⁻³ ♦driven at 138 rpm (24) Kyowanol M ™ 6.80 × 10⁻⁸ 1.2 ×10⁻² ⋄not driven (25) MP-Ethoxypropanol ™ 6.24 × 10⁻⁵ 8.0 × 10⁻⁴ ⋄notdriven (26) BP-Ethoxypropyl Acetate ™ 3.10 × 10⁻⁸ 6.0 × 10⁻⁴ ♦driven at143 rpm (27) Sansocizer E-4030 ™ 5.46 × 10⁻⁹ 2.0 × 10⁻² ♦driven at 58rpm (28) Sansocizer DOTP ™ 6.20 × 10⁻¹⁰ 4.0 × 10⁻² ♦driven at 35 rpm(29) TBP 2.20 × 10⁻⁶ 2.2 × 10⁻³ ⋄not driven (30) TBXP 1.10 × 10⁻⁵ 9.0 ×10⁻³ ⋄not driven (II) (31) CLP 7.80 × 10⁻⁶ 3.0 × 10⁻² ⋄not driven (32)Ethyl 2-methylacetoacetate 1.00 × 10⁻⁴ 5.0 × 10⁻⁴ ⋄not driven (33)1-Ethoxy-2-acetoxypropane 4.41 × 10⁻⁷ 4.0 × 10⁻⁴ ♦driven at 161 rpm (34)DCM-40 ™ 2.60 × 10⁻⁵ 5.5 × 10⁻³ ⋄not driven (35) Linalyl acetate 1.82 ×10⁻⁹ 1.3 × 10⁻³ ♦driven at 258 rpm (36) Dibutyl decanedicate 1.40 × 10⁻⁹7.0 × 10⁻³ ♦driven at 132 rpm

[0236] The relation between the conductivity and the viscosity set forthin table 3 is shown in FIG. 1, in which the conductivity and theviscosity of the fluid which was driven are represented by symbol ♦, andthe conductivity and the viscosity of the fluid which was not driven arerepresented by symbol ⋄.

Example 2

[0237] The SE type ECF motor of Example 1 was filled with2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (compound (24), tradename: Kyowanol M), and a direct-current-voltage of 6 kV was applied.Since 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate had a conductivityσ of 6.80×10⁻⁸ S/m and a viscosity η of 1.2×10⁻² Pa·s at 25° C. as shownin Tables 3 and 4, the SE type ECF motor was not driven.

[0238] Separately, the SE type ECF motor was filled with 2-ethylhexylpalmitate (compound (19), trade name: Exepal EH-P), and adirect-current-voltage of 6 kV was applied. Since 2-ethylhexyl palmitatehad a conductivity σ of 2.60×10⁻¹⁰ S/m and a viscosity η of 9.5×10⁻³Pa·s at 25° C. as shown in Tables 3 and 4, the SE type ECF motor was notdriven.

[0239] Then, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (compound(24), trade name: Kyowanol M) and 2-ethylhexyl palmitate (compound (19),trade name: Exepal EH-P) were mixed in a mixing ratio of 1:4 by weightto prepare a homogeneous mixture (37).

[0240] This mixture (37) was measured on the conductivity and theviscosity in the same manner as in Example 1. As a result, the mixturehad a conductivity σ of 2.60×10⁻⁹ S/m and a viscosity η of 9.8×10⁻³ Pa·sat 25° C.

[0241] Then, the SE type ECF motor was filled with the mixture (37), anda direct-current-voltage of 6 kV was applied at 25° C. in the samemanner as described above. As a result, the motor was driven at 38 rpm.

[0242] The results are set forth in Table 4.

Example 3

[0243] The SE type ECF motor of Example 1 was filled with diallylmaleate (DAM, compound (4)), and a direct-current-voltage of 6 kV wasapplied. Since diallyl maleate had a conductivity σ of 7.80×10⁻⁷ S/m anda viscosity η of 2.5×10⁻³ Pa·s at 25° C. as shown in Tables 3 and 4, theSE type ECF motor was not driven.

[0244] Separately, the SE type ECF motor was filled with butyl stearate(compound (22), trade name: Exepal BS), and a direct-current-voltage of6 kV was applied. Since butyl stearate had a conductivity σ of3.10×10⁻¹⁰ S/m and a viscosity ηof 8.5×10⁻³ Pa·s at 25° C. as shown inTables 3 and 4, and the SE type ECF motor was not driven.

[0245] Then, diallyl maleate (compound (4), DMA) and butyl stearate(compound (22), trade name: Exepal BS) were mixed in a mixing ratio of1:4 by weight to prepare a homogeneous mixture (38).

[0246] This mixture (38) was measured on the conductivity and theviscosity in the same manner as in Example 1. As a result, the mixturehad a conductivity σ of 4.17×10⁻⁹ S/m and a viscosity η of 5.0×10⁻³ Pa·sat 25° C.

[0247] Then, the SE type ECF motor was filled with the mixture (38), anda direct-current-voltage of 6 kV was applied at 25° C. in the samemanner as described above. As a result, the motor was driven at 140 rpm.

[0248] The results are set forth in Table 4. TABLE 4 Compound or Conduc-Visco- Electric Mixture tivity sity Sensitivity ( ™: trademark) (S/m)(Pa · s) (6 kV) (24) Kyowanol M ™ 6.80 × 10⁻⁸ 1.2 × 10⁻² ⋄ (not driven)(19) Exepal EH-P ™ 2.60 × 10⁻¹⁰ 9.5 × 10⁻³ ⋄ (not driven) (37) (24) +(19) 2.60 × 10⁻⁹ 9.8 × 10⁻³ ♦ (driven at 38 (24): (19) = 1:4 rpm)  (4)DAM 7.80 × 10⁻⁷ 2.5 × 10⁻³ ⋄ (not driven) (22) Exepal BS ™ 3.10 × 10⁻¹⁰8.5 × 10⁻³ ⋄ (not driven) (38) (4) + (22) 4.17 × 10⁻⁹ 5.0 × 10⁻³ ♦(driven at 140 (4): (22) = 1:4 rpm)

[0249] The relation between the conductivity and the viscosity set forthin Table 4 is shown in FIG. 1, in which the conductivity and theviscosity of the fluid which was driven are represented by symbol ♦, andthe conductivity and the viscosity of the fluid which was not driven arerepresented by symbol ⋄.

Example 4

[0250] The SE type ECF motor of Example 1 was filled with 2-ethylhexylbenzyl phthalate (compound (15), trade name: Placizer B-8), and adirect-current-voltage of 6 kV was applied with maintaining thetemperature of the 2-ethylhexyl benzyl phthalate at 25° C. Since2-ethylhexyl benzyl phthalate had a conductivity σ of 1.10×10⁻⁸ S/m anda viscosity η of 7.8×10⁻² Pa·s at 25° C. as shown in Tables 3 and 5, theSE type ECF motor was not driven.

[0251] Then, 2-ethylhexyl benzyl phthalate (compound (15), trade name:Placizer B-8) was heated to 100° C. to obtain a heated product (39).This heated product (39) was measured on the conductivity and theviscosity at 100° C. As a result, the heated product had a conductivityσ of 9.90×10⁻⁹ S/m and a viscosity η of 3.5×10⁻³ Pa·s at 100° C.

[0252] Then, a direct-current-voltage of bkV was applied in the samemanner as in Example 1, except that the SE type ECF motor was filledwith the heated product (39) and the temperature of the product(2-ethylhexyl benzyl phthalate) was maintained at 100° C. As a result,the motor was driven at 21 rpm.

[0253] The results are set forth in Table 5. TABLE 5 Compound or Conduc-Visco- Electric Mixture tivity sity Sensitivity ( ™: trademark) (S/m)(Pa · s) (6 kV) (15) Placizer B-8 ™ 1.10 × 10⁻⁸ 7.8 × 10⁻² ⋄ (notdriven)  (25° C.) (39) Placizer B-8 ™ 9.90 × 10⁻⁹ 3.5 × 10⁻² ♦ (drivenat 21 rpm) (100° C.)

[0254] The relation between the conductivity and the viscosity set forthin Table 5 is shown in FIG. 1, in which the conductivity and theviscosity of the fluid which was driven are represented by symbol ♦, andthe conductivity and the viscosity of the fluid which was not driven arerepresented by symbol ⋄.

Example 5

[0255] A SE type ECF motor shown in FIG. 2 was fabricated, wherein thefluid container made of an acrylic resin had an outer diameter of 10 mm,an inner diameter of 8 mm and a height of 20 mm, and the vane rotor had8 vanes made of an acrylic resin. This SE type ECF motor was providedwith four pairs of electrodes each made of wire having a diameter of 0.3mm. The interval angle between the electrodes was set to be 22.5° (1.5mm). The rotating shaft of the vane rotor is made of wire having adiameter of 1 mm. As the bearing, ball bearings were used to reducefriction torque. To the rotating shaft, a plastic disc was fitted asshown in FIG. 4, and the rotation of the disc was detected by means of aphotointerrupter to measure the rotational circumferential speed. Asshown in FIG. 4, a resistance of 1 MΩ was provided in series between theSE type ECF motor and the ground to obtain a current from the electricpotential. In order to protect the measuring device, Zener diode wasconnected in parallel with the resistance, and the voltage was measuredthrough a voltage follower using an OP amplifier having sufficientlyhigh input impedance.

[0256] The SE type ECF motor was filled with dibutyl decanedioate. Then,a voltage was applied with varying the applied voltage by 1 kV in therange of 0 to 6 kV, to measure the rotational speed and the current.

[0257] The SE type ECF motor began to rotate at the applied voltage of 2kV, and the rotational speed was increased in proportion to the appliedvoltage.

[0258] The relation among the applied voltage, the rotational speed andthe current is shown in FIG. 7. As is clear from FIG. 7, the rotationalspeed was increased in proportion to the applied voltage.

Example 6

[0259] The SE type ECF motor shown in FIG. 2 was filled with dibutyldecanedioate as the electro-sensitive movable fluid. Then, adirect-current-voltage was applied between the electrodes with varyingthe applied voltage to 2.5 kV, 3.0 kV, 3.5 kV, 4.0 kV, 4.5 kV, 5.0 kV,5.5 kV and 6.0 kV, to measure the rotational speed of the vane rotor.The results are shown in FIG. 8(a).

Example 7

[0260] In the SE type ECF motor shown in FIG. 2, dibutyl decanedioatewas used as the electro-sensitive movable fluid and the number of vaneswas varied to 2, 3, 4, 6 or 8. In each case, the rotational speed of thevane rotor was measured (applied voltage: 6 kV). The results are shownin FIG. 8(b). As the number of vanes was increased, the rotational speedwas increased. As the interval between the electrodes was narrowed, therotational speed was increased. As the number of pairs of the electrodeswas increased, the rotational speed was increased. The rotational speedwas independent from the interval between the pairs of electrodes.

Example 8

[0261] In the SE type ECF motor shown in FIG. 2, dibutyl decanedioatewas used as the electro-sensitive movable fluid, the diameter of thefluid container was varied to 20 mm, and the diameter of the vane rotorwas varied to 6 mm, 13 mm or 17 mm. In each case, the rotational speedand the output torque were measured. For measuring the output torque, anapparatus shown in FIG. 11 was used. The results are shown in FIG. 8(c).

[0262] Referring to FIG. 11, the number 30 represents a SE type ECFmotor or a RE type ECF motor, the number 31 represents a strain gauge,the number 32 represents a micrometer, the number 33 represents amicrometer head, the number 34 represents a rotating shaft, and thenumber 35 represents a wire. The wire 35 is spread between two poleseach fitted to the corresponding strain gauge 31 respectively, and iswound once on the rotating shaft 34. When the rotating shaft 34 rotates,a difference of tension force of the wire is produced. The difference ofthe tension force between the right and left sides is measured by thestrain gauge to determine the output torque (rotational torque). Thatis, the load torque given when the flexible wire 35 is wound once on therotating shaft 34 of the SE type ECF motor is a friction torque (DF/2).The difference of the tension force (T₁-T₂) of the wire 35 is assumed toequal to the friction force F acted on the output shaft, so that theoutput torque is calculated as D(T₁-T₂)/2.

[0263] As is clear from FIG. 8(c), the vane rotor 18 was efficientlyrotated by the jet flow of dibutyl decanedioate, and the electric energywas able to be transformed to rotational energy. With increase of therotational speed, the output torque was reduced linearly. The current inthe measurement of the output torque was 2.2 μA irrespective of the vanerotor diameter and the output torque.

Example 9

[0264] In the SE type ECF motor shown in FIG. 2, dibutyl decanedioatewas used as the electro-sensitive movable fluid, and the diameter of thefluid container and the diameter of the vane rotor were varied to 12 mmand 9 mm, respectively, 16 mm and 13 mm respectively, or 20 mm and 17mm, respectively. In each case, the rotational speed and the outputtorque were measured. The results are shown in FIG. 8(d). When the ratioof the diameter of the vane rotor 18 to that of the fluid container 2was set to be constant 0.8, a higher output torque at the samerotational speed was obtained with a smaller diameter of the fluidcontainer 2. The current was almost the same and the values thereof were4.5 μA for 12 mm (fluid container diameter), 3.2 μA for 16 mm, and 2.2μA for 20 mm. Based on the results shown in FIG. 8(d), when the fluidcontainer 2 having a diameter of 12 mm was used, the output power was0.30 mW and the energy conversion efficiency was 1.1%. It was confirmedthat when the ratio of the vane rotor diameter to the fluid containerdiameter was constant, a higher output torque was obtained with asmaller diameter of the fluid container. This result suggests that theSE type ECF motor is suitable for miniaturization.

[0265] From the output power obtained above, an output power density tothe volume of the motor was calculated. The volume of the motor wascalculated as a value of vane rotor length×fluid container sectionalarea. The results are shown in FIG. 9(a). As is clear from FIG. 9(a),the output power density was remarkably improved by miniaturizing the SEtype ECF motor. Therefore, the SE type ECF motor is suitable forminiaturization.

Example 10

[0266] In the RE type ECF motor shown in FIG. 3, dibutyl decanedioatewas used as the electro-sensitive movable fluid and the interval anglebetween the rod type electrodes was varied to 11°, 23° or 45°. In eachcase, the rotational speed and the output torque were measured. Theresults are set forth in Table 9(b). The interval angle between theelectrodes hardly influenced the rotational speed of the cylindricalrotor 46. That is, the characteristics of the RE type ECF motor are notdetermined only by an equivalent electric field strength obtained bydividing the voltage by the interval between the electrodes. Assumingthat the circumferential rate of the rotor with no-load is almost equalto a flow rate of the dibutyl decanedioate, the circumferential rate isabout 120 mm/S, and this suggests that a higher rotational speed may beobtained by miniaturizing the RE type ECF motor.

Example 11

[0267] In the RE type ECF motor shown in FIG. 3, dibutyl decanedioatewas used as the electro-sensitive movable fluid, the interval anglebetween the electrodes was set to be 23°, the diameter of thecylindrical rotor was made to be 10 mm, and the diameter of the fluidcontainer was varied to 14 mm, 20 mm, 30 mm or 40 mm. In each case, therotational speed and the output torque were measured. The results areset forth in FIG. 9(c). When the diameter of the fluid container 41 was14 mm, a high output torque was obtained, but the rotational speed inthe no-load state was decreased. The reason is assumably that because ofa narrow gap between the fluid container 41 and the cylindrical rotor46, the jet flow of the dibutyl decadedioate is able to be efficientlytransformed to the rotary motion owing to the viscous force of thefluid, while the loss of energy is increased because of the viscousforce, resulting in that a high rotational speed is not obtainedparticularly in the no-load state.

Example 12

[0268] In the RE type ECF motor shown in FIG. 3, dibutyl decanedioatewas used as the electro-sensitive movable fluid, the diameter of thefluid container and the diameter of the vane rotor were varied to 14 mmand 10 mm, respectively, 20 mm and 16 mm respectively, or 24 mm and 20mm, respectively. In each case, the rotational speed and the outputtorque were measured. The results are shown in FIG. 9(d). With a smallerdiameter of the fluid container 41, the output torque at the samerotational speed was increased and the change of the rotational speedfor the load torque was increased. Based on the results shown in FIG.9(d), the maximum value of the output power was 0.32 mW when thediameter of the fluid container and the diameter of the cylindricalrotor of the RE type ECF motor were 14 mm and 10 mm, respectively.

Example 13

[0269] In the SE type ECF motor shown in FIG. 2, dibutyl decanedioatewas used as the electro-sensitive movable fluid, and the diameter of thefluid container and the diameter of the vane rotor were varied to 14 mmand 10 mm, respectively, 20 mm and 16 mm respectively, or 24 mm and 20mm, respectively. In each case, the rotational speed and the outputtorque were measured. The results are shown in FIG. 10(a). In comparisonwith Example 12, the output power of the SE type ECF motor was higherthan that of the RE type ECF motor, but the RE type ECF motor wassuperior to the SE type ECF motor in the change of the rotational speedfor the load torque.

Example 14

[0270] In the RE type ECF motor shown in FIG. 3, dibutyl decanedioatewas used as the electro-sensitive movable fluid, the diameter of thefluid container was made to be 30 mm, and the diameter of thecylindrical rotor was varied to 10 mm, 16 mm or 20 mm. In each case, therotational speed and the output torque were measured. The results areshown in FIG. 10(b). When the diameter of the cylindrical rotor 46 was20 mm, a high output torque was obtained.

Example 15

[0271] In the RE type ECF motor shown in FIG. 3, dibutyl decanedioatewas used as the electro-sensitive movable fluid, and the diameter of thefluid container and the diameter of the vane rotor were varied to 20 mmand 10 mm, respectively, 30 mm and 16 mm respectively, or 40 mm and 20mm, respectively. In each case, the rotational speed and the outputtorque were measured. The results are shown in FIG. 10(c). It was foundthat with a smaller diameter of the fluid container 41, the outputtorque at the same rotational speed was increased and the change of therotational speed for the load torque was increased.

Example 16

[0272] A SE type ECF motor with the same structure as shown in FIG. 2and larger than the motor of Example 1 was used. This SE type ECF motoris provided with a bottomed cylindrical container having an innerdiameter of 26 mm as the fluid container and a vane rotor having 6 vaneseach being large in proportion to the container's size. The fluidcontainer was provided with 8 electrodes (3 a to 3 h), wherein 3 a and 3e were set to be positive electrodes and the remainders 3 b, 3 c, 3 d, 3f, 3 g and 3 h were grounded so as to be negative electrodes.

[0273] The fluid container was filled with about 17 ml of2,2,4-trimethyl-1,3-pentanediol diisobutyrate represented by thefollowing formula (trade name: Kyowanol D, available from Kyowa HakkoKogyo Co., Ltd.), and a direct-current-voltage of 5 kV or 6 kV wasapplied.

[0274] When the direct-current-voltage was applied, the rotor 18 having6 vanes began to rotate and continued to rotate during the applicationof voltage. When the voltage was varied to 6 kV from 5 kV, therotational speed was increased. The results are set forth in Table 6.The measurement of the current in Examples 15 to 29 was carried out bymeans of a commercially available ammeter. The lower limit of themeasurement by this ammeter is 0.05 mA. By the expression “<0.05unmeasurable” in the following tables is meant that the current waslower than the lower limit of the measurement by the ammeter. TABLE 6Voltage (DC-kV) 5.0 6.0 Rotational speed 72 100 (rpm) Current (mA) <0.05unmeasurable <0.05 unmeasurable

Example 17

[0275] The procedure of Example 16 was repeated except that glyceroltriacetate represented by the following formula (alias “triacetin”,available from Daihachi Chemical Industry Co., Ltd.) was used in thesame amount in place of 2,2,4-trimethyl-1,3-pentanediol diisobutyrate(trade name: Kyowanol D, available from Kyowa Hakko Kogyo Co., Ltd.) andthe applied voltage was varied to 6.0 kV.

[0276] When a direct-current-voltage of 6 kV was applied, the rotor 18began to rotate at 60 rpm. The pointer of the ammeter was confirmed toslightly move at the moment the voltage was applied. However, thecurrent was lower than the lower limit (0.05 mA) of the measurement bythe ammeter and the accurate value was unable to be measured.

Example 18

[0277] The procedure of Example 16 was repeated except that a containerprovided with 16 electrodes at the same intervals on the inner surfcewas used in place of the container provided with 8 electrodes at thesame intervals on the inner surifce.

[0278] The fluid filled in the container was2,2,4-trimethyl-1,3-pentanediol diisobutyrate which was the same fluidas used in Example 16.

[0279] Of the electrodes, the first, fifth, ninth and thirteenthelectrodes clockwise numbered were set to be positive ones, and thesecond, sixth, tenth and fourteenth electrodes were grounded so as toset to be negative ones. Then, a direct-current-voltage of 6 kV wasapplied. The third, fourth, seventh, eighth, eleventh, twelfth,fifteenth and sixteenth electrodes were dummy electrodes. The intervalbetween the positive and negative electrodes in the case of using 16electrodes was ½ of the interval in the case of using 8 electrodes.

[0280] When a direct-current-voltage of 6 kV was applied, the rotor 18began to rotate and continued to rotate at 158 rpm during theapplication of voltage. The pointer of the ammeter was confirmed toslightly move at the moment the voltage was applied. However, thecurrent was lower than the lower limit (0.05 mA) of the measurement bythe ammeter and the accurate value was unable to be measured, similarlyto the case of using 8 electrodes.

[0281] As a result, it was confirmed that the rotational speed of therotor was increased with a smaller interval between the positive andnegative electrodes.

[0282] Further, when the direct-current-voltage was applied in themanner described in Examples 16 to 18, rise of the electro-sensitivemovable fluid along either of the positive and negative electrodes wasobserved.

Example 19

[0283] The procedure of Example 16 was repeated except that 15 ml of2-methoxy-l-methylethyl acetate represented by the following formula(trade name: Arcosolve PMA, available from Kyowa Hakko Kogyo Co., Ltd.)was used as the electro-sensitive movable fluid. That is, in thisexample, a vane rotor provided with 6 vanes at the same intervals wasused, 15 ml of 2-methoxy-1-methylethyl acetate represented by thefollowing formula was used as the electro-sensitive movable fluid, theelectrodes 3 a and 3 e were set to be positive electrodes and theremainders were grounded so as to be negative ones, and adirect-current-voltage was applied.

[0284] As a result, the vane rotor began to rotate immediately after theapplication of voltage and continued to rotate during the application ofvoltage. The relation between the applied voltage and the rotationalspeed is set forth in Table 7. As is clear from Table 7, the currentduring the application of voltage was lower than the lower limit (0.05mA) of the measurement by the ammeter. TABLE 7 Voltage (DC-kV) 5.0 6.0Rotational speed 109 152 (rpm) Current (mA) <0.05 unmeasurable <0.05unmeasurable

Example 20

[0285] The vane rotor was rotated in the same manner as in Example 19,except that a mixture of the compounds represented by the followingformulas was used as the electro-sensitive movable fluid in place of2-methoxy-1-methylethyl acetate (trade name: Arcosolve PMA, availablefrom Kyowa Hakko Kogyo Co., Ltd.).

(Mixing ratio 90% by weight: 10% by weight)

[0286] That is, this electro-sensitive movable fluid was a mixture ofisomers of propylene glycol monoethyl ether acetate (trade name: BPEthoxypropyl Acetate, available from Kyowa Hakko Kogyo Co., Ltd.). Therelation between the applied voltage and the rotational speed is setforth in Table 8. As is clear from Table 8, the current during theapplication of voltage was lower than the lower limit (0.05 mA) of themeasurement by the ammeter. TABLE 8 Voltage (DC-kV) 5.0 6.0 Rotationalspeed 61 106 (rpm) Current (mA) <0.05 unmeasurable <0.05 unmeasurable

Example 21

[0287] The electro-sensitive movable fluid used in Example 20 was amixture of two compounds, and the fluid showed good electricsensitivity. In this example, one of the compounds,1-ethoxy-2-acetoxypropane represented by the following formula, was usedas the electro-sensitive movable fluid.

[0288] That is, the procedure of Example 19 was repeated except that1-ethoxy-2-acetoxypropane (available from Wako Junyaku K. K.) which isone of the compounds of the mixture used in Example 20 was used singlywithout mixing it with any other components or adding any othercomponents. The relation between the applied voltage and the rotationalspeed is set forth in Table 9. As is clear from Table 9, the currentduring the application of voltage was lower than the lower limit (0.05mA) of the measurement by the ammeter. TABLE 9 Voltage (DC-kV) 5.0 6.0Rotational speed 82 180 (rpm) Current (mA) <0.05 unmeasurable <0.05unmeasurable

Example 22

[0289] A direct-current-voltage of 5.0 kV was applied in the same manneras in Example 19, except that dibutyl diglycol adipate represented bythe following formula (trade name: BXA, available from Daihachi ChemicalIndustry Co., Ltd.) was used in place of 2-methoxy-1-methylethyl acetate(trade name: Arcosolve PMA, available from Kyowa Hakko Kogyo Co., Ltd.).

[0290] As a result, the rotor began to rotate immediately after theapplication of voltage and continued to rotate during the application ofvoltage. However, the rotational speed was not constant and one rotationtook 2.3 to 6.5 seconds.

[0291] In addition, there was also observed sudden stop of the rotor orvigorous right-left vibration of the rotor followed by the normal rotarymotion. The cause of such behaviors has not been clarified yet, butthose behaviors seem to be phenomena specifically observed in some ofthe compounds represented by the formula [II]. In each case, the currentduring the application of voltage was lower than the lower limit (0.05mA) of the measurement by the ammeter.

Example 23

[0292] The applied voltage and the rotational speed were measured in thesame manner as in Example 19 by means of the same SE type ECF motor asin Example 19, except that 3-methoxy-3-methylbutyl acetate representedby the following formula (trade name: Solfit Acetate, available fromKuraray Co., Ltd.) was used as the electro-sensitive movable fluid.

[0293] The results are set forth in Table 10. TABLE 10 Voltage (DC-kV)5.0 6.0 Rotational speed 75 110 (rpm) Current (mA) <0.05 unmeasurable<0.05 unmeasurable

Example 24

[0294] The applied voltage and the rotational speed were measured in thesame manner as in Example 19 by means of the same SE type ECF motor asin Example 19, except that diethylene glycol butyl ether acetaterepresented by the following formula (trade name: Butyl CarbitolAcetate, available from Union Carbide) was used as the electro-sensitivemovable fluid.

[0295] The results are set forth in Table 11. TABLE 11 Voltage (DC-kV)5.0 6.0 Rotational speed 82 135 (rpm) Current (mA) <0.05 unmeasurable<0.05 unmeasurable

Example 25

[0296] The compound represented by the following formula [D] or [D-1],each of which is very similar to the compound of the formula [III], isalso employable as the electro-sensitive movable fluid of the invention.

[0297] The compounds represented by the above formulas are compoundswherein X⁴ and Y⁴ are linked by an ester linkage. X⁴ and Y⁴ may be thesame as or different from each other. X⁴ and Y⁴ are each basically amonovalent hydrocarbon group and may contain a hetero atom such as anoxygen atom, a nitrogen atom or a sulfur atom. Further, X⁴ and Y⁴ mayhave a functional group such as a double bond and may be linear orbranched. However, the compound represented by the formula [D] containsno halogen atom (e.g., chlorine atom, fluorine atom, bromine atom,iodine atom). By virtue of the absence of halogen atom in theelectro-sensitive movable fluid of the invention, even when theelectro-sensitive movable fluid is applied to an apparatus made of ametal, the corrosion of the apparatus does not take place, and themovable fluid is safe to the human body or the environment even when itis decomposed. The presence of a small amount of halogen atom had beenthought to be essential to the movable fluid in the past, but as aresult of studies by the present inventors, it has been found that thestructure was more dominative than the presence of halogen atom in theelectricity-sensitive working fluids. Accordingly, the presence of ahalogen atom is not essential to the electro-sensitive movable fluid ofthe invention. On the contrary, in consideration of corrosion of theapparatus or bad influences on the human body and the environment, it ispreferable that no halogen atom is contained in the electro-sensitivemovable fluid of the invention.

[0298] Of the compounds represented by the formula [D], those having anepoxy group present in the following formula or 3,7-dimethyl-1,6-octadien-3-yl acetate represented by the followingformula (trade name: Linalyl Acetate, available from Kurarey Co., Ltd.)are preferable from the viewpoint of the action of converting electricenergy to rotational energy.

Example Using Compound Having Epoxy Group

[0299]

[0300] The SE type ECF motor having a vane motor with 6 vanes, which wasused in Example 19, was filled with about 15 ml of 9,10-epoxy butylstearate (trade name: Sansocizer E4030, available from New JapanChemical Co., Ltd.) to set the SE type ECF motor.

[0301] The electrodes 3 a and 3 e were set to be positive electrodes andthe remainders were grounded so as to be negative ones. Then, adirect-current-voltage of 6.0 kV was applied.

[0302] As a result, the SE type ECF motor began to rotate immediatelyafter the application of voltage and continued to rotate at 45 rpmduring the application of voltage. The current during the application ofvoltage was lower than the lower limit (0.05 mA) of the measurement bythe ammeter.

Example Using 3,7-dimethyl-1,6-octadien-3-yl acetate

[0303]

[0304] A direct-current-voltage of 6 kV was applied in the same manneras in Example 19, except that the SE type ECF motor having a vane motorwith 6 vanes, which was used in Example 19, was filled with3,7-dimethyl-1,6-octadien-3-yl acetate represented by the above formula(trade name: Linalyl Acetate, available from Kurarey Co., Ltd.).

[0305] As a result, the SE type ECF motor began to rotate immediatelyafter the application of voltage and continued to rotate at 126 rpmduring the application of voltage. The current during the application ofvoltage was lower than the lower limit (0.05 mA) of the measurement bythe ammeter.

Example 26

[0306] The electrode 53 of the RE type ECF motor shown in FIG. 3 was setto be a positive electrode and the electrode 52 thereof was set to be anegative electrode. Supply of the electric power to the electrodesarranged on the cylindrical rotor was carried out through the rotationalcontact point of mercury. Arrangement of the electrodes and polaritiesthereof are shown in FIG. 3. The bearing section at the center of thebottom of the fluid container was provided with ball bearings to reducefriction of the shaft.

[0307] As shown in FIG. 3, a cylindrical rotor having a diameter of 20mm and a height of 50 mm was arranged in the fluid container, and thecontainer was filled with the following electro-sensitive movable fluidsindividually to completely immerse the whole rotor. The length of theelectrode provided on the rotor was 50 mm, and the interval angle θbetween the electrodes was 22.5°.

[0308] When a direct-current-voltage of 6.0 kV was applied, the rotorbegan to rotate clockwise, and the rotary motion of the rotor wascontinued during the application of voltage. When the polarity of theapplied voltage was reversed, the rotor began to rotatecounterclockwise, and the counterclockwise rotation was continued.

[0309] The rotational speed (rad/s) for each movable fluid was measured.The results are set forth in Table 12.

[0310] The types I to V of the electro-sensitive movable fluids shown inTable 12 have structures represented by the following formulas.

[0311] In the above formula, X¹ is a divalent group of 1 to 14 carbonatoms which may have either a branched chain, an ether linkage or anester linkage, and Y¹ and Z¹ are each independently an alkyl group or 1to 5 carbon atoms which may have a branch.

[0312] In the above formula, X² is a divalent alkyl group of 2 to 9carbon atoms which may have a branch, Y² is a divalent alkyl group of 1to 6 carbon atoms, Z² is an alkyl group of 1 to 6 carbon atoms which mayhave a branch, n is an integer of 1 to 4, m is an integer of 1 or 2.When m is 1, A is a hydrogen atom. When m is 2, the compound of thisformula is a symmetric dimer having A as a bonding hand in which groupseach represented by (Z²—O—(X²—O)_(n)—CO—Y²)— are directly bonded to eachother.

[0313] In the above formula, X³ is a monovalent group having carbonatoms (a), oxygen atoms (b) and hydrogen atoms (2a+1 −2b) wherein a isan integer of 1 to 25, b is 0, 1, 2 or 3, and 2a+1>2b, and Y³ is ahydrocarbon group of 1 to 14 carbon atoms which may have a branchedchain and/or a carbon-to-carbon double bond.

[0314] In the above formulas of the types IV and V, R¹ and R² are eachindependently a hydrocarbon group which may contain an atom other thancarbon and hydrogen, R¹ and R² may be the same as or different from eachother, and X is a divalent group represented by the following formula[VI] or [VII]:

[0315] wherein R³ and R⁴ are each a hydrocarbon group which may have abranch and to which an atom other than carbon and hydrogen may bebonded, R³ and R⁴ may be the same as or different from each other, q andr are each independently 0 or an integer of 1 or more, when q or r is 0,R³ and R⁴ are each independently a single bond, p is 0 or an integer of1, 2 or 3, a cyclic structure regulated by p may have a substituent, andthe cyclic structure may be partly or wholly hydrogenated;

—C_(n)H_((2n-2m))—  [VII]

[0316] wherein n is an integer of 2 or more, and m is the number ofdouble bonds contained in this group.

[0317] In the above formula, Z⁴ is an alkyl group of 1 to 5 carbon atomswhich contains any one of

[0318] a single bond and —O—CH₂— and

[0319] and which may have a branch, X⁴ is a hydrocarbon group of 1 to 17carbon atoms which may have a branch, Y⁴ is a hydrocarbon group of 1 to20 carbon atoms which may have a branch, and X⁴ and Y⁴ may have a heteroatom and/or an unsaturated bond. TABLE 12 Rotational speed TypeElectricity-sensitive working medium (rad/s) I2,2,4-Trimethyl-1,3-pentanediol diisobutyrate 16.5

I Glycerol triacetate 9.6

II 2-Methoxy-1-methoxy-1-methylethyl acetate 25.0

II Propylene glycol monoethyl ether acetate (mixture) 17.4

II 3-Methoxy-3-methylbutyl acetate 18.0

II Diethylene glycol butyl ether acetate 22.1 C₄H₉—O—(CH₂—CH₂O)₂—CO—CH₃III 9,10-Epoxy butyl stearate 7.3

III 3,7-Dimethyl-1,6-octadien-3-yl acetate 29.0

IV Dibutyl itaconate 20.3

IV Dibutyl decanedioate 14.0 C₄H₉—O—CO—(CH₂)₈—CO—O—C₄H₉ IV Butyl benzylphthalate 5.8

V Methyl acetyl ricinoleate 6.9

[0320] In the use of each of the electro-sensitive movable fluids, thevalue of the direct current in the measurement of the rotational speedwas lower than the lower limit (0.05 mA) of the measurement by theammeter, and the accurate value was unable to be measured.

Example 27

[0321] The output torque (basic characteristics of the RE type ECF motorof the invention) was measured by the use of a measuring device shown inFIG. 11. In FIG. 11, the number 30 represents a RE type ECF motor.

[0322] The RE type ECF motor 30 used for the measurement had a structureshown in FIG. 3. The inner diameter of the fluid container was 30 mm. Asfor the cylindrical rotor, three kinds of rotors having a height of 50mm and having different diameters, i.e., rotor A 10 mm in diameter,rotor B 16 mm in diameter and rotor C 20 mm in diameter, were used. Theinterval angle between the electrodes was 22.5°. The rotor C was thesame rotor as used in Example 26.

[0323] As the electro-sensitive movable fluid, dibutyl decanedioatewhich was the same fluid as used in Example 26 was used. The fluidcontainer was filled with the movable fluid to completely immerse thewhole cylindrical rotor.

[0324] Then, a direct-current-voltage of 6.0 kV was applied. As aresult, each of the rotors A to C began to rotate immediately after theapplication of voltage. The rotational speed, the output torque and thecurrent were measured with respect to each rotor.

[0325] The results are set forth in Tables 13 to 15, respectively. TABLE13 Inner diameter of fluid container: 30 mm Rotor A (diameter: 10 mm)Rotational speed Output torque Current (rad/s) (μN · m) (μA) 30.6 0.012.0 20.9 5.5 12.0 14.0 12.3 12.0 11.3 14.7 12.0

[0326] TABLE 14 Inner diameter of fluid container: 30 mm Rotor B(diameter: 16 mm) Rotational speed Output torque Current (rad/s) (μN ·m) (μA) 17.9 0.0 7.0 16.5 2.6 7.0 12.3 8.8 7.0 9.1 17.2 7.0

[0327] TABLE 15 Inner diameter of fluid container: 30 mm Rotor C(diameter: 20 mm) Rotational speed Output torque Current (rad/s) (μN ·m) (μA) 12.6 0.0 6.0 11.6 3.2 6.0 8.7 13.3 6.0 8.1 20.8 6.0

[0328] As is clear from the results, with a larger diameter of thecylindrical rotor, a higher output torque was obtained. The reason isassumably that because of the narrow gap between the fluid container(housing) and the cylindrical rotor, the jet flow of the fluid producedbetween the electrodes is efficiently transformed to the rotary motionby means of the viscous force of the fluid.

Example 28

[0329] Fluid containers (housings) having inner diameters of 20 mm and40 mm were prepared. In the fluid container having an inner diameter of20 mm, the rotor A having a diameter of 10 mm which was used in Example27 was set, while in the fluid container having an inner diameter of 40mm, the rotor C having an inner diameter of 20 mm which was used inExample 27 was set. Then, the rotational speed, the output torque andthe current were measured in the same manner as in Example 27.

[0330] The results are set forth in Table 16 and 17, respectively. TABLE16 Inner diameter of fluid container: 20 mm Rotor A (diameter: 10 mm)Rotational speed Output torque Current (rad/s) (μN · m) (μA) 30.6 0.012.0 19.3 4.8 12.0 11.4 16.1 12.0 7.9 19.3 12.0

[0331] TABLE 17 Inner diameter of fluid container: 40 mm Rotor C(diameter: 20 mm) Rotational speed Output torque Current (rad/s) (μN ·m) (μA) 14.0 0.0 6.0 10.1 9.9 6.0 9.2 10.5 6.0

[0332] As is clear from the result, the ratio of the housing diameter tothe rotor diameter in this example was 2.0, while the ratio of thehousing diameter to the rotor diameter in Table 15 of Example 27 was1.9. It was confirmed from the results that with decrease of thediameter of the housing, namely, with miniaturization of the housing,the output torque at the same rotational speed was increased and thechange of the rotational speed for the output torque was increased.

Example 29

[0333] The rotational speed, output torque and the current were measuredin the same manner as in Example 27, except that a fluid containerhaving an inner diameter of 24 mm was used and three kinds of rotorshaving different interval angles of the electrodes, i.e., rotor C-2having an interval angle θ of 11.30°, rotor C-3 having an interval angleof 45.0° and rotor C having an interval angle of 22.5°, were used.

[0334] The results are set forth in Table 18 to 20, respectively. TABLE18 Inner diameter of fluid container: 24 mm Rotor C-2 (diameter: 20 mm,θ: 11.3°) Rotational speed Output torque Current (rad/s) (μN · m) (μA)10.6 0.0 12.0 9.0 30.5 12.0 7.7 56.0 12.0 6.3 83.7 12.0

[0335] TABLE 19 Inner diameter of fluid container: 24 mm Rotor C(diameter: 20 mm, θ: 22.5°) Rotational speed Output torque Current(rad/s) (μN · m) (μA) 12.6 0.0 6.0 12.0 9.4 6.0 10.5 35.5 6.0 8.6 58.46.0

[0336] TABLE 20 Inner diameter of fluid container: 24 mm Rotor C-3(diameter: 20 mm, θ: 45.0°) Rotational speed Output torque Current(rad/s) (μN · m) (μA) 12.6 0.0 5.6 10.3 21.0 5.6 9.2 43.0 5.6 8.5 52.25.6

Example 30

[0337] The rotational speed was measured in the same manner as inExample 26, except that a mixture of dibutyl decanedioate (97.5% byweight) and petroleum benzine (2.5% by weight, available from Nippon OilCo., Ltd.) was used as the electro-sensitive movable fluid. As a result,the rotational speed was 20.2 rad/s, and this speed was biggar ratherthan one containing only dibutyl decanedioate as a movable fluiddescribed in Example 26 (14.0 rad/s). This means that the electricsensitivity of dibutyl decanedioate was improved and provided biggerrotational speed by adding petroleum benzine. The current was lower thanthe lower limit (0.05 mA) of the measurement by the ammeter.

What is claimed is:
 1. An electro-sensitive movable fluid comprising acompound having a conductivity σ and a viscosity η located inside arectangular triangle in a graph showing a relation between aconductivity σ, plotted as abscissa, and a viscosity η, plotted asordinate, of a fluid at the working temperature, said rectangulartriangle having, as vertexes, a point P indicated by the conductivityσ=4×10⁻¹⁰ S/m and the viscosity η=1×10⁰ Pa·s, a point Q indicated by theconductivity σ=4×10⁻¹⁰ S/m and the viscosity η=1×10⁻⁴ Pa·s, and a pointR indicated by the conductivity σ=5×10⁻⁶ S/m and the viscosity η=1×10⁻⁴Pa·s, or comprising a mixture of two or more kinds of compounds, saidmixture being adjusted to have a conductivity σ and a viscosity ηlocated inside said rectangular triangle.
 2. The electro-sensitivemovable fluid as claimed in claim 1, wherein the point P is indicated bythe conductivity σ=5×10⁻¹⁰ S/m and the viscosity η=8×10⁻¹ Pa·s, thepoint Q is indicated by the conductivity σ=5×10⁻¹⁰ S/m and the viscosityη=2×10⁻⁴ Pa·s, and the point R is indicated by the conductivityσ=2.5×10⁻⁶ S/m and the viscosity η=2×10⁻⁴ Pa·s.
 3. The electro-sensitivemovable fluid as claimed in claim 1 or claim 2, wherein the compound isa chain or branched, substantially dielectric fluid compound containingmolecular end group composed of alkyl groups, outer ends of said groupsinactivated by hydrogen atoms bonding to the carbon atoms, saidmolecular end groups being united by bonding to each other at the innerends, in which the bonding hand of each carbon atom for constituting theend groups with the sealed ends is bonded to at least one hetero atomand further linked to a straight-chain divalent hydrocarbon group, whichmay have a hetero atom and may have a branch, through the hetero atom,or is bonded to a divalent hydrocarbon group which may have a heteroatom or may have a branch.
 4. The electro-sensitive movable fluid asclaimed in claim 3, wherein the compound is at least one compoundselected from compounds represented by the following formulas [II],[II], [III], [IV] and [V]:

wherein X¹ is a divalent group of 1 to 14 carbon atoms which may haveeither a branched chain, an ether linkage or an ester linkage, and Y¹and Z¹ are each independently an alkyl group or 1 to 5 carbon atomswhich may have a branch;

wherein X² is a divalent alkyl group of 2 to 9 carbon atoms which mayhave a branch, Y² is a divalent alkyl group of 1 to 6 carbon atoms, Z²is an alkyl group of 1 to 6 carbon atoms which may have a branch, n isan integer of 1 to 4, m is an integer of 1 or 2, and in case of m=1, Ais a hydrogen atom; in case of m=2, said compound of this formula beinga symmetric dimer having A as a bonding hand in which groups eachrepresented by (Z²—O—(X²—O)_(n)—CO—Y²)—are directly bonded to eachother;

wherein X³ is a monovalent group having a carbon atoms, b oxygen atomsand 2a+1-2b hydrogen atoms (a is an integer of 1 to 25, b is 0, 1, 2 or3, and 2a+1 >2b), and Y³ is a hydrocarbon group of 1 to 14 carbon atomswhich may have a branched chain and/or a carbon-to-carbon double bond;

wherein R¹ and R² are each independently a hydrocarbon group which maycontain an atom other than carbon and hydrogen, and may be the same asor different from each other, and X is a divalent group represented bythe following formula [VI] or [VII]:

wherein R³ and R⁴ are each a hydrocarbon group which may have a branchand to which an atom other than carbon and hydrogen may be bonded, R³and R⁴ may be the same as or different from each other, q and r are eachindependently 0 or an integer of 1 or more, when q or r is 0, R³ and R⁴are each independently a single bond, p is 0 or an integer of 1, 2 or 3,a cyclic structure regulated by p may have a substituent, and the cyclicstructure may be partly or wholly hydrogenated;—C_(n)H_((2n−2m))—  [VII] wherein n is an integer of 2 or more, and m isthe number of double bonds contained in this group.
 5. A method ofdriving the electro-sensitive movable fluid as claimed in any one ofclaims 1 to 4, wherein said movable fluid contains a small amount of ahydrocarbon compound having 5 to 10 carbon atoms.
 6. A method of movingan electro-sensitive movable fluid, comprising applying a voltagebetween at least two electrodes arranged in an electro-sensitive movablefluid to move the electro-sensitive movable fluid in the direction ofone electrode to the other electrode.
 7. A method of converting electricenergy to mechanical energy, comprising the steps of arranging at leastone pair of electrodes in an electro-sensitive movable fluid, applying avoltage between the electrodes to form jet flow of the electro-sensitivemovable fluid at a velocity corresponding to the applied electricenergy, and converting fluid energy of the jet flow of theelectro-sensitive movable fluid to mechanical energy capable of beingtaken out.
 8. A method of controlling energy conversion, comprising thesteps of arranging at least one pair of electrodes in a container filledwith an electro-sensitive movable fluid, applying adirect-current-voltage between the electrodes to convert electric energyto fluid energy of the electro-sensitive movable fluid by changing theapplied direct-current-voltage in a range of 0.1 V to 10 kV to controlthe flow velocity and the flow direction of the electro-sensitivemovable fluid in proportion to the applied direct-current-voltage, andconverting the fluid energy of the movable fluid to mechanical energycapable of being taken out.
 9. The method as claimed in claim 5 or 6,wherein at least one pair of electrodes and a rotor are arranged in acontainer filled with the electro-sensitive movable fluid and adirect-current-voltage applied between the electrodes is changed in arange of 0.1 V to 10 kV to control a rotational speed and a rotationaldirection of the rotor in proportion to the applieddirect-current-voltage.
 10. The method as claimed in any one of claims 6to 9, wherein the electro-sensitive movable fluid comprises a compoundhaving a conductivity σ and a viscosity η located inside a rectangulartriangle in a graph showing a relation between a conductivity σ plottedas abscissa, and a viscosity η, plotted as ordinate, of a fluid at theworking temperature, said rectangular triangle having, as vertexes, apoint P indicated by the conductivity σ=4×10⁻¹⁰ S/m and the viscosityη=1×10⁰ Pa·s, a point Q indicated by the conductivity σ=4×10⁻¹⁰ S/m andthe viscosity η=1×10⁻⁴ Pa·s, and a point R indicated by the conductivityσ=5×10⁻⁶ S/m and the viscosity η=1×10⁻⁴ Pa·s, or comprises a mixture oftwo or more kinds of compounds, said mixture being adjusted to have aconductivity σ and a viscosity η located inside said rectangulartriangle.
 11. The method as claimed in any one of claims 7 to 10,wherein the electro-sensitive movable fluid is dibutyl decanedioate. 12.A motor for electro-sensitive movable fluid, including a container to befilled with an electro-sensitive movable fluid, a lid to close thecontainer by being engaged with the open top of the container, acylindrical rotor rotatable inside the container around a rotating shaftborne by a shaft hole provided at the center of the lid and a bearingsection provided at the center of the bottom of the container, pluralfirst electrodes which are electrically connected with externalelectrode terminals through the rotating shaft at the upper part of thecylindrical rotor and arranged in the vertical direction on the surfaceof the cylindrical rotor, and second electrodes which are electricallyconnected with external electrode terminals through the rotating shaftat the lower part of the cylindrical rotor and arranged in non-contactwith the first electrodes and in the vertical direction on the surfaceof the cylindrical rotor.
 13. The motor for electro-sensitive movablefluid as claimed in claim 12, wherein the plural first and secondelectrodes arranged in the vertical direction on the surface of thecylindrical rotor are each made of a conductive material and theinterval angle between the electrodes is in the range of 1° to 180°. 14.A method of driving a motor for electro-sensitive movable fluid, saidmotor including a container to be filled with an electro-sensitivemovable fluid, a lid to close the container by being engaged with theopen top of the container, a cylindrical rotor rotatable inside thecontainer around a rotating shaft borne by a shaft hole provided at thecenter of the lid and a bearing provided at the center of the bottom ofthe container, plural first electrodes which are electrically connectedwith first external electrode terminals through the rotating shaft atthe upper part of the cylindrical rotor and arranged in the verticaldirection on the surface of the cylindrical rotor, and second electrodeswhich are electrically connected with second external electrodeterminals through the rotating shaft at the lower part of thecylindrical rotor and arranged in non-contact with the first electrodesand in the vertical direction on the surface of the cylindrical rotor;which comprises applying a direct-current-voltage between the first andsecond electrodes to produce jet flow of the electro-sensitive movablefluid in the fluid container and thereby rotate the cylindrical rotortogether with the electrodes.